srf is a web server providing
Spaced Repetition
Flashcards,
based loosely on Anki.
It runs on node with a local sqlite database. All resources being local, it can run while offline.
$ npm install -g @ig3/srf
This provides the command srf.
- Get an Anki deck (e.g. from AnkiWeb, or wherever)
- Import the Anki deck into srf:
srf import anki_deck.apkg - Run the srf server:
srf - Browse srf: http://localhost:8000
- Click the Study button (shortcut: space bar)
- Review the card then click Flip (shortcut: space bar)
- Rate the card: Click Fail, Hard, Good or Easy (shortcuts: j, k, l, ;)
- Repeat: review, flip then rate each card
You study cards. Each card has a front and a back. First you view the front and try to remember what is on the back. Then you flip the card over to see the back: to see if you remembered correctly. Finally, you rate how well you remembered the card: 'Fail', 'Hard', 'Good' or 'Easy'.
The scheduler presents a few new cards each day. The number of new cards is adjusted automatically, to keep total study time between 30 and 60 minutes.
When you have studied all the cards due for review and reached the limit on new cards, you will return to the Home page, until there are more cards to study.
The scheduler is configurable: all the limits and parameters can be adjusted to your preferences and ability. Do you want to study more or less each day? Change targetStudytime. Want a different limit on new cards? Change maxNewCardsPerDay. And many more. There are very few hard coded parameters, and even those are easy to change: just checkout the repository and change them. It's all JavaScript, HTML, CSS and a few handlebars templates. And if you want something more fundamentally different, you can replace the scheduler. It was ease of tinkering with the scheduler that motivated me to write this.
There are many places to download shared Anki decks and many tools for generating them. AnkiWeb is one source. Search for 'shared Anki decks' or 'generate Anki decks'
The home page shows statistics of your study:
- cards reviewed and minutes studied in the past 24 hours
- cards due and predicted minutes to study in the next 24 hours
- study time per day: a forward looking average used to determine new card mode and a short term historic average
- new cards per day: new cards in the past 24 hours and a short term historic average
- percent of cards that you got correct (i.e. not rated Fail)
- number of cards due and overdue for review
- chart of study time per hour: past 24 hours and next 24 hours
The status at the top right includes:
- Traffic lights for new cards:
- Green (go): new cards at intervals and if there are no due cards
- Yellow (slow): new cards at intervals
- Red (stop): no new cards
- Cards due
- New cards in the past 24 hours
- Minutes studied in the past 24 hours
- Predicted minutes to study in the next 24 hours
To study a card, click the Study button or press the space bar.
The study button will always present a card for study, ignoring the limits of the scheduler.
The space bar will present a card for study or reload the home page, according to the determination of the scheduler.
The buttons at the bottom of the page are:
- Admin: to access the admin page
- Stats: to review various statistics of your study history
- Help: to review the help file - mostly a link to this README
The content of the card front is variable.
Status at top right is the same as the home page.
At the bottom of the page are a set of buttons:
- Flip: to flip the card over to the back (shortcut: space bar)
- Help: to review the help file
- Edit: to edit the card content
- Play: to replay audio, if the card has audio
- Stop: to stop studying and return to the home page
The content of the card back is also variable.
Status at top right is the same as the home page.
At the bottom of the page are a set of buttons:
- Fail: if you couldn't remember the card (shorcut: j)
- Hard: if you could remember the card but it was hard (shortcut: k)
- Good: if you could remember the card reasonably well (shortcut: l)
- Easy: if you could remember the card very easily (shortcut: ;)
- Help: to view the help file
- Edit: to edit the card content
- Play: to replay audio, if the card has audio
- Stop: to stop studying and return to the home page
After you rate the card (Fail, Hard, Good or Easy) the front of the next card will be presented, you you will be returned to the home page if there are no more cards to study.
There are several ways to create cards:
- Import Anki .apkg or .colpkg file
- Import CSV files
- Add them one at a time via the browser
- Direct database update
Cards are the basic elements of study. They are produced from fieldsets, transformed by templates.
A fieldset is a set of name/value pairs that you want to remember in relationship to each other, stored as JSON.
For example:
{
"Country": "Canada',
"Capital": "Ottawa",
"Continent": "North America"
"Area': "over 9.98 million square kilometres",
"Population": "38 million"
}
A template is a pair of Mustache templates for the front and back of a card that include some of the fields in the fieldset, and some css for styling the card.
For example:
Front: The <span class="keyword">capital</span> of {{Country}} is?
Back: {{Capital}}
css: .keyword { font-style: italic; }
A single template can be used to produce cards from many fieldsets.
Templates are grouped into sets identified by templateset name.
Each fieldset is related to a templateset and one card is produced for each template in the templateset.
You study the cards. The cards are produced automatically when you add or edit fieldsets or templates.
The order that cards are presented as new cards is determined by their ordinal (ord), which is copied from the fieldset.
The easiest way to create cards is to import an Anki Packaged Deck. This will import the Anki cards, notes and note types into srf. However, srf does not support all the features of Anki so not all Anki decks will work in srf. For example, srf does not support cloze deletion so any deck that includes cloze deletion notes will not work.
If you have been using Anki, you can export your own decks. Be sure ti include media when you export your decks. If you include scheduling information, it will be preserved.
Anki collection packages and shared decks can include review logs. These will be imported and merged with existing logs. Daily stats will be cleared and recalculated to including the new revlog entries.
You can download a shared Anki deck from AnkiWeb or use various tools to produce Anki Packaged Deck files from other sources.
Srf doesn't distinguish decks. If you import multiple decks or a deck collection, all the cards will appear in a single pool of cards in srf. If you want to keep decks separate, you can import each deck into a separate srf database.
Note that srf only supports simple cards. In particular, Cloze notes are not supported. See below for what is/isn't supported. Start with something basic.
To import an Anki packaged deck:
$ srf import <shared_deck.apkg>
To import an Anki deck collection:
$ srf import <deck_collection.colpkg>
Create two CSV files:
- templates.csv
- fieldsets.csv
Import each file with:
$ srf import templates.csv
$ srf import fieldsets.csv
The templates determine which cards are produced and how the are presented. One card is produced for each template with matching templateset value.
The fields for a template are:
- templateset - the name of the templateset, must match same on fieldset
- name - the name of the template
- front - the mustache template code for the front of the card
- back - the mustache template code for the back of the card
- css - the CSS for rendering the card, common to front and back
Make a CSV file with these headings and appropriate data.
For example:
templateset,name,front,back,css
Basic,Card 1,{{Front}},{{Back}},".card { Background-color: red; }"
Basic,Card 2,{{Back}},{{Front}},".card { Background-color: red; }"
You can create many templatesets and each templateset can have as many templates as you like. One card will be produced for each template with templateset matching that of a fieldset.
The fields for a fieldset are:
- guid - optional guid that uniquely identifies the fieldset
- templateset - the templateset for rendering the fieldset
- fields - the fields data as a JSON string
- ord - an ordinal number for sorting the fieldsets
guid will default to md5 checksum of the concatenation of the templateset and fields values.
ord will default to the row number * 10.
For example:
templateset,fields
Test1,"{""Front"": ""Who you gonna call?"", ""Back"": ""Ghost Busters!""}"
Test1,"{""Front"": ""Where's Waldo?"", ""Back"": ""Hold on a sec... I'm still looking.""}"
You can have as many fields as you want in your templates and fieldsets.
Read below for details of all the options for the templates. They are Mustache templates with all the field values available.
If the fieldsets refer to media files (images, audio, video, etc.), you will have to copy these to the media directory: ~/.local/share/srf/media by default.
For example, a field might include an image with something like:
<img src=\"my-image.png\" />, or an audio file with something like:
[sound:my-audio.mp3].
You can create templates and fieldsets manually in the browser. The interface is crude, but it's an option.
On the home page, click Admin to view the admin page.
On the admin page, click Templates, Template Sets or Field sets to see a list of the corresponding items.
Click on an item in the list to edit it, or click the New button to add a new item to the list.
When you edit a fieldset, the fields you can set are determined from the templates in the selected templateset: every field included in any template in the templateset. You can't set fields that are not included in any template. If you want to set another field, include it in at least one of the templates.
The database structure is simple. You can write your own application to add cards to the srf database.
The database is sqlite3.
By default, the database is at ~/.local/share/srf/srf.db and media files are in ~/.local/share/srf/media.
Add templates by adding records to the template table.
Add fieldsets by adding records to the fieldset table.
See the database description for a description of the database and details of these tables.
After modifying template or fieldset tables, generate missing cards and delete orphaned cards by running fix:
$ srf fix
$ srf
Listening on http://:::8000
Alternatively, create a systemd service file (e.g. ~/.config/systemd/user/srf.service) similar to:
[Unit]
Description=Spaced Repetition Flashcards
[Service]
Type=simple
Restart=on-failure
WorkingDirectory=/tmp
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=srf
ExecStart=bash -l -c srf
[Install]
WantedBy=default.target
Then enable and run the service:
$ systemctl --user enable srf
$ ssytemctl --user start srf
With this done, your srf server will run whenever you login.
Browse to http://localhost:8000/
Click the Study button or press the space bar to study a card.
When you study a card, the front of the card is displayed. The content of the front of the card depends on the template and the fieldset.
When you are ready, you flip the card to see the back of the card. See below for details of the back of the card.
Keyboard shortcut: space-bar
Flip the card over, to show the back of the card. This is the usual action when reviewing a card: view the front, then flip it to review the back and rate the card.
Show the help file.
Edit the card. This opens a new window with fields to edit the fieldset from which the card is derived. It is a bit crude but allows simple edits.
keyboard shortcut: p
If the card has audio, play it again.
Return to the home page without completing review of the card.
After you view the front of the card and flip it over, the back is displayed. The content of the back is determined by the template and the fieldset.
The back of the card has buttons for rating how well you remember the card: Fail, Hard, Good and Easy.
The button you click determines when the card will be scheduled for review. Each button displays the new interval: the time until the card will be due for review.
keyboard shortcut: j
If you didn't remember the card and want to review it again soon, click Fail. This reduces the interval for reviewing the card. The new interval (the time until the card is due for review) is half the previous interval with a maximum interval of 1 day.
keyboard shortcut: k
If you did remember the card but it was difficult to remember, click Hard. This reduces the interval for rewviewing the card but not as much as Fail. The new interval is 80% of the previous inerval with a maximum interval of 1 week.
keyboard shortcut: l
If you remembered the card well, click Good. This will, hopefully, be the button you click most often. This increases the interval for reviewing the card.
Calculation of the new interval is more complicated for Good. The minimum new interval is 5 minutes and the maximum new interval is 1 year. Between these limits, the new interval depends on the ease factor of the card. The ease factor is the exponentially weighted moving average of your previous ratings. The weights are 0, 1, 1.5 and 2 for Fail, Hard, Good and Easy respectively. Thus the factor ranges from 0 to 2 and it will change a bit each time you review the card.
If you rate the card Good several times, the ease factor will tend towards 1.5 and the new interval will tend towards 150% of the previous interval.
On the other hand, if you have rated the card Fail many times, the ease factor might be quite low and even if you rate the card Good, the new interval might be less than the previous interval. However, even in this case, the ease factor will increase so that after a few Good reviews the interval will be increasing.
keyboard shortcut: ;
If it was too easy to remember the card and you don't want to waste your time reviewing again too soon, click Easy. The new interval will be 150% of what it would be for Good.
Show the help file.
Edit the templateset the card is generated from.
Replay any audio for the back of the card.
Stop studying without completing review of the card: return to the home page.
I used Anki for a couple of years but wanted to change the scheduler. An Anki addon to add a new scheduler was impossible because Anki addons are Python code but the scheduler implementation is partially in Python and partially in Rust back-end code. Even limited modifications to the existing schedulers (e.g. Anki - limit new) were difficult and time consuming to maintain due to frequent changes to the Anki internals. It was easier to write this and get the scheduler I wanted than to maintain the Anki addon that provided only part of what I wanted.
The srf scheduler:
- prioritizes cards with shorter intervals over those with longer intervals
- regulates the introduction of new cards automatically
- is written entirely in JavaScript and is easy to modify
srf is able to import Anki decks that use only basic features of Anki. Not all field and media types are supported, but enough for many decks / cards to work.
Spaced Repetition for Efficient Learning provides an overview and links to research on spaced repetition.
srf provides only a small subset of the features of Anki: enough for my purposes: studying language on a single device, but without support for synchronizing multiple devices or distinguishing decks / multiple topics of study.
The srf scheduler does not suffer from Ease Hell.
The srf scheduler has an equivalent to Anki ease factor for each card but it is simpler: it is the exponentially weighted moving average of the weighted answers. The default answer weights are 0, 1, 1.5 and 2 for Fail, Hard, Good and Easy and the default decay factor is 0.95, but these are all configurable. By default, the range of the ease factor is 0.0 through 4.0: somewhat equivalent to Anki ease factors 0% to 200%. With srf the ease factor never gets 'stuck' at an unreasonably low setting. It always adapts to the recent ease of the card.
The srf scheduler does not suffer from Backlog Hell.
The srf scheduler has two ways of sorting cards:
- by ascending interval
- by ascending due time
The sort is determined randomly each time a due card is selected with the probability of sorting by due time being config.probabilityOldestDue, which defaults to 0.2.
This strategy balances studying cards in they order they become due with focusing on the cards with minimum interval. It makes a difference only when clearing a backlog. It allows the cards with the shortest intervals to be studied on time, despite the backlog. At the same time, it allows the most overdue cards to be studied, gradually clearing the backlog.
New cards are presented before due cards if total study time the past 24 hours is less than config.minStudyTime.
New cards are presented at intervals, interleaved with due cards, if total study time the past 24 hours is less than config.targetStudytime.
$ git clone https://github.com/ig3/srf.git
$ cd srf
$ npm install
$ node bin/cmd.js import <export file>
$ node bin/cmd.js
The import supports Anki exports and shared decks (.apkg files). When I migrated from Anki, I exported all decks as an Anki deck package (*.apkg), including media, then imported this into srf.
Browse to http://localhost:8000/.
The home page presents some basic study statistics:
- The number of cards reviewed and minutes studied in the past 24 hours
- The number of cards due and estimated minutes to study in the next 24 hours
- Study time per day: short term used to determine new card mode / historic average
- New cards per day: past 24 hours / historic average
- New cards during the past 24 hours
- The percentage of correct (not 'Fail') responses to mature cards in the past 14 days
- The number of cards due and overdue (due more than 24 hours ago)
- The time until the next card is due
- A histogram of study time per hour through past and next 24 hours
If there is a card available for study, the 'Study' button will appear. Click it to study a card. After studying a card, the next card will be presented, until there are no more cards to be studied and the home page is displayed again. Alternatively, click the space bar: shortcut for Study.
The scheduler determines when a card is due to be studied. Each time a card is reviewed, the scheduler sets a new time when it is due to be studied again. The cards to be studied are all those which are past their due time. If it is more than 24 hours past their due date and time, they are considered overdue.
It's like an assembly line: you will sometimes be waiting for the next card to study, and you will sometimes have a backlog of cards to catch up. While you don't want to get too far behind, it is OK to accumulate cards to review. Studying to clear the backlog once per day will work well. While there is nothing wrong with studying in multiple sessions each day, don't obsess about reviewing every card that comes due each day. It is OK to leave them until the next day, or even longer.
The data is in ~/.local/share/srf by default, including database (srf.db) and media files. The database is ~/.local/share/srf/srf.db. Media files are in ~/.local/share/srf/media.
At the top right of the home page and front and back pages, there is a status indicator. Green, yellow or red depending on new card mode: Green if new cards will be presented interleaved with due cards and if there are no cards due; Yellow if new cards will be presented interleaved with due cards; and Red if no new cards will be presented. Below this are counts of cards due, minutes of study the past 24 hours and minutes of study the next 24 hours (estimated).
Study a card. This will select a card according to the scheduling algorithm if there is a card due to be studied. If no card is due to be selected, a new card will be presented. If there are no more unseen cards, then the card with the earliest due date will be presented, even if that is in the future. This button will always yield a card to study.
Reload the home page.
View the admin page, with links to administer templates, template sets and field sets, and view configuration.
View the statistics page.
This will be documentation, if I ever write it.
Links to the administration pages:
View a list of all templates in the system. Click on a template to edit it.
Each template is linked to a template set and should have a unique name among the templates linked to that template set. There are three attributes:
Front: handlebars template code for the front of the card.
Back: handlebars template code for the back of the card.
CSS: CSS that will be loaded to the front and back.
All the fields of the template/fieldset are available. For example, if the
fieldset includes a field English then include this in the template with
{{English}}.
The set of fields are defined in the template set definition.
View a list of all template sets in the system.
The view is read-only. To change them, add or edit the templates.
The fields of a templateset are all the fields of all the templates in the templateset. If you add a field to one of the templates, it will be added to the templateset.
View a list of all field sets in the system. Click on a field set to edit it. Click the New button to add a field set.
A field set is a collection of field values that populate cards. The set of fields is defined in the linked template set.
Each fieldset must be linked to a Template set. The set of fields is defined in the template set. If you change the template set after setting field data, the field data will be lost.
To attach media files, put the cursor into the field value input where the media file is to be attached, then click the Attach button and select the file containing the media data.
At the moment, the only supported media types are image/jpeg and
audio/mpeg. These are inserted as img tags and audio respectively.
A read-only view of the loaded configuration.
The Stats Page is available from the Home Page by clicking the Stats button. It shows some basic statistics about study performance.
This is the number of new cards viewed in the current day, short term (past 7 days) average of new cards per day and long term (since the beginning of study) average of new cards per day.
This is the total number of distinct cards that have been seen at least once since the start of study.
The stage is determined by card interval. The stages are: Unseen, New, Learning, Mature and Mastered.
This is the percentage of 'correct' responses (a.k.a. not Fail) for cards with intervals between config.matureThreshold and config.maxInterval, reviewed in the window config.percentCorrectWindow.
Cards with maximum interval are excluded on the premise that they are mastered and it is not performance on these cards that should be regulated, but rather performance on mature cards (Unconcious Competence).
Maybe this should also include the learning cards, but these are excluded on the premise that while learning the error rate will be relativley high and the regulation effectively regulates how quickly cards progress through learning to mastered, even though the learning cards are not included in the calculation of percent correct.
Card intervals are adjusted according to the difference between the average percent correct and config.percentCorrectTarget. If average percent correct is less than the target then intervals are shortened, making cards due sooner. If it is more than the target then intervals are lengthened, making cards due later.
This is the average time for each review of a card. It includes small gaps between reviews. It is the total study time for the day divided by the number of reviews.
This is the total number of distinct cards viewed today and the number of cards due later in the same day. The day is the calendar day in local time.
The total number of cards viewed today is a count of cards not reviews. A card might be reviewed multiple times in a day but this counts the cards, not the reviews.
The cards due later in the same day are those cards scheduled for review before the end of the day in local time. This includes cards that are currently due or overdue. This does not included cards that will be rescheduled to be viewed again later in the same day.
This is the number of reviews to be completed before the next new card will be presented, counting down at each review, and the current minimum number of cards to be reviewed between each new card.
This is the total time spent studying today.
This is average daily study time, averaged over the past week (actual study time) and coming week (estimated based on cards due and recent performance).
The time until the earliest due card is due. This will be negative if there is a card due in the past: if there is currently one or more cards due for study.
This is the number of new cards presented each day since the start of study
This is the total number of card views each day since the start of study.
This is the total study time per day since the start of study.
This is a stacked chart of cards per stage: New, Learning, Matured and Mastered. The stages are distinguished by interval.
- New: 0 < interval < config.learningThreshold
- Learning: config.learningThreshold <= interval < config.matureThreshold
- Mature: config.matureThreshold <= interval < config.maxInterval
- Mastered: config.maxInterval <= interval
This is the number of cards due for review each day, looking forward from today.
This is the number of cards with the given interval in days. There are two lines: Adjusted Interval and Unadjusted Interval. The Adjusted Interval is the interval after adjustment for percent correct. The Unadjusted Interval is the interval as set when the card was last viewed. The adjusted interval is the interval that will be the basis for calculation of the interval after the next review.
usage:
srf --help
srf [options...] [run]
srf [options...] import <filename>
srf [options...] backup
srf [options...] fix
Run the server. This is the default.
Import an Anki apkg or colpkg file, or a csv file containing template or fieldset data.
Create a backup of the srf database.
The server makes a backup of the database each time it starts and then once every 24 hours if it runs that long.
The backups are in the same directory as the database, with timestamp appended to their name.
This performs several 'fixes':
- create any missing cards from fieldsets and templates and delete any cards for which there is no longer a fieldset and template.
- fix revlog entries:
- make revlog IDs unique and monotonic increasing
- set 'lastinterval' to 'interval' of the previous revlog entry for the card
- set 'interval' of the last revlog entry for a card to the 'lastinterval' of the card
- set revdate according to the id
- add missing counts of cards by stage to dailystats
Display usage and exit.
Set the port that the srf server listens on.
Default is 8000.
Set the root directory, in which the database and media files are located.
Default is ~/.local/share/srf
If the given directory is absolute (i.e. begins with '/') it is used as
given. If it is relative (i.e. does not begin with '/') it is relative to
~/.local/share.
For example: /tmp/testing would use that directory but testing would
use ~/.local/share/testing and testing/a would use
~/.local/share/testing/a.
Media files are located in the media subdirectory of this directory.
The srf database is, by default, srf.db in this directory, but see option
--database below.
Set the configuration filename.
Default is config.json
If the given path is absolute (i.e. begins with '/') it is used as given. If it is relative (i.e. does not begin with '/') it is relative to the path of the --directory option.
Set the sqlite3 database name.
Default is ~/.local/share/srf/srf.db or, if --directory is specified then srf.db in that directory.
If the given path is absolute (i.e. begins with '/') it is used as given - the database file can be outside the data directory. If it is relative, then it is relative to the path of the --directory option.
The directory to contain the database is created if it doesn't exist.
Set the path of the media directory.
Default is media
If the given path is absolute (i.e. begins with '/') it is used as given. If it is relative (i.e. does not begin with '/') it is relative to the path of the --directory option.
The directory is created if it doesn't exist.
Set the path of the htdocs directory.
Default is htdocs
If the given path is absolute (i.e. it begins with '/') it is used as given. If it is relative (i.e. does not begin with '/') it is relative to the path of the --directory option.
This directory contains overrides for the static content of the srf server.
- css/dark.css
- img/dark-go.png
- img/dark-slow.png
- img/dark-stop.png
- img/favicon.png
- img/logo.png
- js/plotly-latest.min.js
- js/sorttable.js
Specify the schedulre plugin to load. The argument will be passed to require() to load the plugin, so it must be something that can be required. Details will depend on how srf and the plugin are installed but the name of a globally installed package or the full path to the scheduler module should both work.
Set the path of the views directory.
Default is views
If the given path is absolute (i.e. it begins with '/') it is used as given. If it is relative (i.e. does not begin with '/') it is relative to the path of the --directory option.
This directory contains overrides for the handlebars templates of the srf server. Templates in this folder will override the default templates.
- back.handlebars
- fieldset.handlebars
- front.handlebars
- help.handlebars
- home.handlebars
- stats.handlebars
- template.handlebars
- templates.handlebars
Configuration files may be put in several places:
- /etc/srf
- /etc/srf.ini
- /etc/srf.json
- /etc/srf/config
- /etc/srf/config.ini
- /etc/srf/config.json
- ~/.config/srf
- ~/.config/srf.ini
- ~/.config/srf.json
- ~/.config/srf/config
- ~/.config/srf/config.ini
- ~/.config/srf/config.json
- ~/.srf
- ~/.srf.ini
- ~/.srf.json
- ~/.srf/config
- ~/.srf/config.ini
- ~/.srf/config.json
- .srf
- .srf.ini
- .srf.json
And, finally, config.json in the directory containing the data
(~/.local/share/srf by default but may be set by option --directory).
Files with extension .json and files without extension are parsed as JSON
after stripping comments from them.
Files with extension .ini are parsed as ini files.
Parameters which are durations may be specified as integer seconds or a
string with units: seconds, minutes, hours, days, weeks or
years, or any prefix of one of these. The units may be separated from the
number by spaces.
For example:
- 10 // 10 seconds
- "10 seconds"
- "5 days"
- "1 day"
- "1 d"
- "1d"
Other parameters are integers.
For example, a json file might be:
{
// Display theme
"theme": "dark",
// Minimum time between related cards (seconds)
"minTimeBetweenRelatedCards": "1 hour"
// Backup retention time (milliseconds)
"backupRetention": "30 days",
// Minimum number of backups to keep
"minBackups": 2,
// Maximum number of backups to keep
"maxBackups": 10,
// The maximum time for viewing a card (seconds).
// Beyond this, any answer is converted to 'again'
"maxViewTime": "2 minutes",
// The maximum interval to when a card is due.
"maxInterval": "1 year",
"maxGoodInterval": "1 year',
"maxEasyInterval": "1 year",
// The interval (seconds) beyond which a card is considered 'learning'
"learningThreshold": '1 week',
// The interval (seconds) beyond which a card is considered 'mature'
"matureThreshold": "21 days",
// The window (seconds) in which to average Percent Correct reviews
"percentCorrectWindow": "1 month",
// The window (seconds) in which to average new cards per day
"newCardsWindow": "2 weeks",
// The minimum number of mature cards in the percent correct window
// at which percent correct is calculated.
"minPercentCorrectCount": 10,
// The target for percent correct reviews
"percentCorrectTarget": 90,
"percentCorrectSensitivity": 0.0001,
// The interval (seconds) between correct factor adjustments
"correctFactorAdjustmentInterval": "1 day",
// The maximum number of new cards in 24 hours.
"maxNewCardsPerDay": 20,
// Minimum study time (seconds) per day
"minStudyTime": "20 minutes",
// Target study time (seconds) per day
"targetStudyTime": "30 minutes",
// The probability of sorting due cards by due instead of inteval
"probabilityOldestDue": 0.2,
// minimum intervals according to responses to reviews
"againMaxInterval": "1 day",
"hardMinInterval": "1 week",
"goodMinInterval": "5 minutes",
"goodMinFactor": 1.1,
"easyMinInterval": "1 days",
// Static interval factors
"againFactor": 0.5,
"hardFactor": 0.8,
"goodFactor": 1.0,
"easyFactor": 1.5,
// Answer weights
"weightFail": 0,
"weightHard": 1,
"weightGood": 1.5,
"weightEasy": 2,
"decayFactor": 0.95
}
default: dark
There is only one theme: dark. But this is only a CSS file. This setting is
just the name of the CSS file, less the .css extension.
default: 1 hour
A template set typically contains several templates. For each field set, a card will be produced for each template in the template set. Thus there will be several cards for each field set.
The set of cards from a single field set are considered related. If one card from the set is reviewed, this is the minimum time before any other card from the set will be presented for review.
default: 30 days
The time to retain database backups. Backups older than this will be deleted.
default: 2
The minimum number of backups to retain, regardless of their age.
default: 10
The maximum number of backups to retain, regardless of their age.
default: 2 minutes
The maximum time for viewing a card. If a card is viewed for longer than this ease will be forced to 'again'.
default: 1 year
The maximum interval (time until next review) for a card.
default: 1 year
The maximum interval (time until next review) for a card that is Good.
default: 1 year
The maximum interval (time until next review) for a card that is Easy.
default: 1 week
The interval beyond which cards are considered to be 'learning' cards rather than 'new' cards. Beyond this threshold, they are scheduled according to the actual interval since they were last reviewed, rather than the scheduled interval.
default: 21 days
This affects the calculation of Percent Correct, which is compared against percentCorrectTarget. Only review of cards with an interval greater than matureThreshold are considered in calculating Percent Correct.
A card is counted as mature (Unconcious Competence) or mastered if its interval is greater than matureThreshold.
default: 1 month
The percentage of 'correct' responses (not 'Fail') is a factor in determining the intervals of cards. All responses within this window are considered in determining the percentage. Results of reviews longer ago than percentCorrectWindow are ignored.
default: 2 weeks
The window in which new cards per day are averaged. The average new cards per day is used to calculate the minimum interval between new cards.
default: 10
The minimum number of mature cards in the percent correct window at which percent correct is calculated.
default: 90
The percentage of 'correct' responses (not 'Fail') is a factor in determining the intervals of cards. The percentCorrectTarget is the target percentage of 'correct' responses.
The interval and due date of cards are adjusted according to the difference between the Percent Correct and this target, multiplied by percentCorrectSensitivity.
Cards actually have two interval values: interval and lastinterval. The interval value is the interval, including any adjustments. The lastinterval value is what the interval was when the card was last reviewed, without any adjustments.
Revlog also has two interval values: interval and lastinterval. But here their values are different. The value of interval is the new interval of the card, after review, based on the ease. The value of lastinterval is the unadjusted interval of the card the last time it was reviewed. It is redundant with the interval value of the previous revlog record for the card but saves a lot of lookup producing the statistics.
default: 0.0001
This determines the sensitivity to the difference between Percent Correct and percentCorrectTarget, when adjusting the interval and due date of learning and mature cards.
default: 20
The maximum number of new cards to be presented within 24 hours.
default: 20 minutes
Minimum daily study time. New cards will be presented until study time in the past 24 hours is more than this.
default: 30 minutes
If total study time for the past 24 hours and predicted study time to study all cards due in the next 24 hours are both less than this, then new cards will be presented, interleaved with due cards. If either exceeds this, then only due cards will be presented.
default: 0.2
The probability that the next due card presented will be the first one due rather than the one with the shortest interval.
default: 1 day
The maximum interval for cards after response 'Fail'.
default: 1 week
This is the maximum interval after responding 'Hard' to a review.
default: 5 minutes
This is the minimum interval after responding 'Good' to a review.
default: 1.1
This is the minimum interval multiplier after responding 'Good' to a review.
default: 1 day
This is the minimum interval after responding 'Easy' to a review.
default: 0.5
After responding 'Fail' to a review, the new interval is the previous interval multiplied by this factor, but with a maximum of againMaxInterval which, by default, is 1 day.
default: 0.8
After responding 'Hard' to a review, the new interval is the previous interval multiplied by this factor, but with a maximum of hardMaxInterval which, by default, is 1 week.
default: 1.0
After responding 'Good' to a review, the new interval is the previous interval multiplied by this factor, the card factor and the 'correct' factor. See 'scheduler' below for details.
default: 1.5
After responding 'Easy' to a review, the new interval is the actual interval since last review (i.e. time since last review, which may be more than the scheduled interval) multiplied by this factor and the card factor.
default: 0
The weight of an answer of Fail when calculating the exponentially weighted moving average of review replies: the card ease factor.
default: 1
The weight of an answer of Hard when calculating the exponentially weighted moving average of review replies: the card ease factor.
default: 1.5
The weight of an answer of Good when calculating the exponentially weighted moving average of review replies: the card ease factor.
default: 2
The weight of an answer of Easy when calculating the exponentially weighted moving average of review replies: the card ease factor.
default: 0.95
The decay factor when calculating the exponentially weighted moving average of review replies: the card ease factor.
ewma(n) = w(n-1) * decayFactor + w(n) * (1 - decayFactor)
Run the web server. This is the default command (i.e. if srf is run without specifying a command on the command line, it runs the webserver).
Import an Anki export (i.e. a .apkg file). This is the primary way to get cards into srf. To migrate from Anki to srf, export decks from Anki, including media, and then import them to srf. Exporting all decks works.
Fix a few inconsistencies in revlog:
- duplicate IDs
- inconsistency between interval and lastinterval
- inconsistency between interval and card interval
This isn't necessary but it ensures greater consistency between the various srf metrics, particularly related to matured cards.
When you study a card, its front side will be presented.
Review the front side and try to recall the corresponding back side.
When you are ready, click the Flip button or click the space bar (shortcut for Flip).
The back side of the card will be displayed, with buttons to indicate how well you remembered the card:
- Fail: you didn't remember the card - you need to see it again soon
- Hard: you remembered the card but it was a bit hard to recall
- Good: you remembered the card
- Easy: you remembered the card but it was too easy
What you should remember, when you see the front side, and what constitutes an adequate recollection is up to you. Some cards may be very specific and fact based while others might be more vague or conceptual. It's up to your own judgement.
Keyboard shortcuts for these are 'j', 'k', 'l' and ';' respectively. These are hard coded, but it is easy to edit the templates in the views directory if you want different shortcuts.
The card is then scheduled for review according to which button you clicked.
If there is another card due for study, the front of it is displayed and you continue your study.
If there are no more cards to be studied at this time the home page is displayed. You can review your progress and return to study when additional cards come due for study.
Every card that is not 'new' has a time when it is due. If this is before the current time, you may study the card. If it is in the future, you may not study the card. You must wait until the card is due for review to study it.
New cards are due if total study time over the past 24 hours is less than config.minStudyTime.
Cards progress through the following stages:
- unseen / unconcious incompetence / UI
- new / concious incompetence / CI
- learning / concious competence / CC
- mature / unconcious competence / UC
- mastered / mastery / M
When you add cards to srf, initially they are unseen. If you add a thousand cards, you probably don't want to study them all on the day you add them. Most of them remain unseen for some time before they are presented as new cards.
If you look at the database. These unseen cards will have an interval of 0. Cards that have been seen have an interval greater than 0. Even if these cards have a due time set, the due time is ignored until they are selected to be presented as new cards.
If the scheduler determines that a new card should be presented, cards with interval = 0 are sorted by ord then id and the first card is presented.
Eventually an unseen card is presented for study for the first time, becoming a 'new' card. It is deemed to be a new card until its interval reaches the learning threshold (config.learningThreshold).
At this stage, your ability to remember the card might be quite volatile. On the one hand, the novelty of it might make it easier to remember. On the other hand, the unfamiliarity of it might make it harder to rememger.
New cards are scheduled according to their scheduled interval, not the actual interval since they were last studied. If a card has a scheduled interval of 30 minutes but you don't study overnight so you don't see it until 10 hours later, it is scheduled on the basis of the scheduled 30 minute interval, not the 10 hour interval.
After familiarizing with a new card, the real work of committing it to long term memory begins. Intervals are still fairly short and your ability to recall the card might be quite sensitive to the actual interval. Reviewing the card a few days late might make the card much more difficult to recall.
During this phase, the card is scheduled according to the actual interval since last review. If you don't review it on time (maybe because of exams or vaction) but when you do you recall it well, it is the actual interval through which you were able to recall it that matters.
Eventually the card is well committed to long term memory. When you see the card, you recognize it immediately, without having to think about it. The the exact interval doesn't make much difference.
By default, cards are considered mature when their interval reaches 21 days. The scheduling algorithm is still applied and the interval will still gradually increase, up to the maximum interval (config.maxInterval) which, by default, is one year.
Finally, cards reach the interval limit. They are mastered.
By default, the interval limit is 1 year (config.maxInterval).
The scheduler is provided by a separate package.
The default scheduler is @ig3/srf-scheduler.
The scheduler can be specified by command line argument --scheduler, the
value of which is the ID or full path of the scheduler module to be loaded.
There are two aspects to the scheduler:
- Determining when a card is due for review
- Determining which card is to be studied next
Cards that have been viewed at least once have a time that they are due for review. Technically, this is stored in the database as a date and time in UTC timezone.
Cards that have never been viewed are called 'new' cards. They do not have a time that they are due for review. They have not been viewed and therefore cannot be reviewed, until after they have been viewed for the first time. For details of when new cards are first presented, see the next section.
The timing, from one review to the next, is the spacing of spaced repetition. The theory is that there is an optimum interval that minimizes the total number of reviews required until a card can be remembered indefinitely: until it has been learned. If the interval is too long, the card is forgotten before it is reviewed: it is not learned. If the interval is too short, the card is easily remembered but reviewing the card too often wastes time that could be used to learn other cards.
Each time a card is studied, whether it is its initial viewing or a later review, the ease with which it was remembered is rated by clicking one of four buttons: Fail, Hard, Good or Easy. The card is then scheduled for review, sooner or later, according to the ease with which it was remembered.
The interval to the next review is determined based on the ease of the current and past reviews.
(Almost) All the scheduling parameters are configurable. The following sections describe the default configuration.
This is for cards that you could not remember: that you want to see again sooner rather than later. The card is scheduled to be reviewed in 30% of the time since it was last reviewed, with a maximum of 1 day.
For example, if you last reviewed a card 1 hour ago but couldn't remember it, it will be scheduled for review in 18 minutes. If you can't remember it again after 18 minutes then it will be scheduled for review in about 5 minutes.
But there is a maximum interval. If it is more than 3 weeks since you last reviewed the card, the new interval will be 1 week.
Cards that were easily remembered at a long interval might become difficult. For example, other similar cards may have been introduced, leading to confusion. This might make the old card difficult until it can be reliably distinguished from the new one.
This is for cards that you could remember but they were too hard: it was too long since the last review and you want to see the card again sooner. The card is scheduled to be reviewed in 50% of the time since it was last reviewed, with a maximum of 1 week.
For example, if you last reviewed a card 10 days ago but found it hard, then it will be scheduled for review in 5 days.
This is for cards that you could remember well: the timing since the last review was good - it was not too hard and not too easy. The card will be scheduled for review after a longer interval.
For new cards (scheduled interval is less than config.learningThreshold), the previous schduled interval is used to calculate the new interval. For learning and mature cards, the actual interval since last review is used. This only makes a difference if there is a delay from scheduled review to actual review. The principle is, if you still remembered it well after a longer interval than scheduled, then use that longer interval to calculate the next interval.
The new interval is the greater of:
- config.goodMinInterval
- the previous interval multiplied by config.goodMinFactor
- the previous interval multiplied by the product of config.goodFactor and the card ease factor.
The card ease factor depends on how easy the card is. It accommodates the fact that some cards are easier than others and that the ease of a card varies with time. It is an exponentially weighted moving average of response values.
The card ease factor is an exponentially weighted moving average of the weighted response values for the card. The weights are 0, 1, 2 and 4 for Fail, Hard, Good and Easy respectivley. The decay factor is 0.9.
The card ease factor is dominated by performance on recent reviews. Older reviews quickly become insignificant. But there is some 'history': the factor is larger for cards that have consistently been Good or Easy and smaller for cards that have consistently been Fail or Hard. A mix of replies will result in an intermediate ease factor.
The range of the card ease factor is 0 to 4. It is a simple multiplier for the interval. If you keep choosing Fail, the factor will drop to 0. If you consistently click Good, the factor will rise to 2: the interval will double after each review. A mix of Good and Hard will result in a factor between 1 and 2, resulting in a slower increase in the interval.
The card ease factor begins at 0 for a new card but will quickly climb with a few Good answers. It is expected that it will typically be between 1 and 2 for a card past the initial learning phase.
The card ease factor is specific to the card. Each card has its own history of answers and its own ease factor. This addresses the issue that some cards are harder or easier than others. This will be reflected in their individual histories of answer and resulting ease factors. On the other hand, cards that were hard will generally become easy with practice and familiarity: they don't stay hard forever. On the other hand, a card that was easy may become hard if other, similar new cards are introduced: it may take time to learn the subtle differences and avoid confusing them. Thus the card ease factor is specific to each card and changes as your success recalling the card changes. And the ease factor changes how quickly the interval grows: from quite slowly (card ease factor around 1) to quite quickly (ease factors closer to 2 or more).
For cards that you remember very well: the time since the last review was too short and you don't want to see the card again so soon.
The new interval is the time since last review multiplied by config.easyFactor (default: 1.5) and the card factor (variable depending on review history), with a minimum interval of 1 day and maximum of 1 year..
For example, if the time since the last review was 1 day and the card factor was 1 then the new interval would be 1.5 days. This would be true even if the previously scheduled interval was less than 1 day.
When you study cards, the scheduler determines which card is to be studied next. There are two possiblities:
- a new card: a card that has not been studied previously
- a card that has been studied previously and is now due for review
Cards that have never been studied are 'unseen' cards. But eventually they are selected to be presented for study: they become a 'new' card.
The scheduler presents new cards to keep daily total study time approximately at config.targetStudyTime.
The new cards are presented at intervals, mixed in with review cards.
New cards are not presented if:
- total study time in the past 24 hours is more than the target
- estimated study time to review all cards due in the next 24 hours is more than the target
- there are overdue cards
- config.maxNewCardsPerDay new cards have been seen in the past 24 hours
New cards start with a minimal interval. If they remain hard, the interval will continue minimal, until you have reviewed the card enough times to begin to recall it. Once you start clicking Good or Easy, the card's ease factor will increase and the rate of increase of the interval will increase accordingly. If the interval doubles at each review, with a series of Good responses, it will soon be many days between reviews. If the card is easy and the reviews become tedious, an answer of Easy will increase the interval more quickly, with a minimum of at least 1 day, and faster increases going forward.
It is normal to have a small backlog: a set of cards past due to be studied. The only way to avoid it is to be studying all day: studying each card as soon as it is due. But this is impractical.
If you have one study period each day (a perfectly reasonably schedule) then you will start each day with a small backlog: cards that came due since you finished studying the previous day.
If you take a vaction (lucky you!), are busy with exams, work or other priorities, you might not study for a few days or a few weeks. When you return to study, you might have a large backlog: many cards due to study.
The scheduling algorithm makes it easy to work through the backlog, whether it is small or large.
When selecting a due card, the scheduler selects either cards that were due first or cards with the shortest interval. The probability of getting a card that was due first is config.probabilityOldestDue which defaults to 0.2.
The selection is slightly randomized: one of the next 5 cards due is returned.
If your backlog is too large, you may not be able to review all due cards in a day. It may take you several days to clear the backlog. The scheduler allows you to cope with this, providing a balance between studying the most overdue cards and studying cards with the shortest intervals on time.
While you have a backlog (cards that were due more than 24 hours ago) no new cards will be shown. There is no value in making the backlog larger. You can return to learning new cards after you clear your backlog.
You can override the scheduler and study a new card at any time by clicking the New Card button on the home page.
If a card is more than 24 hours past its due time, it is deemed to be
overdue. When there are overdue cards, no new cards will be presented.
The scheduler must provide the following methods:
- getCountCardsDueToday
- getIntervals
- getNewCardMode
- getNextCard
- getNextDue
- getNextNew
- getStatsNext24Hours
- getTimeNextDue
- review
Returns the number of cards that are due before the end of the day in local timezone.
Takes a card object as argument.
Returns an object with attributes for each ease: fail, hard, good and easy, the values being the new interval for the given card if that ease is selected.
Returns the mode: 'go', 'slow' or 'stop', for presenting new cards. Mode
go is the most aggressive: new cards are presented if there is no due
card, or at intervals if there are due cards. Mode 'slow' presents new
cards only at intervals between due cards. Mode 'stop' indicates that new
cards will not be presented. See the scheduler documentation for details of
when these modes pertain.
Returns a card object or undefined if there is no card that should be presented. The card may be a due card or a new card. See the scheduler documentation for details of when new or due cards are presented.
Takes a boolean which can be set to true to override limits on presenting due cards.
Returns a card object or undefined if there is no due card that should be presented.
See the scheduler documentation of details of when cards are due and how the card to be presented is selected, if there are multiple cards due.
Returns a card object of undefined if there are no more new cards.
See the scheduler documentation for details of how the unseen cards are sorted to select the next new card to be presented.
Returns an objects with properties:
- count: the number of cards due in the next 24 hours
- time: extimated time to review these cards, based on recent performance
- minReviews: minimum reviews between new cards in 'slow' mode
- reviews: number of reviews since the last new card
Returns the due time (seconds since the epoch) of the card with the earliest due time.
Updates the given card and produces a revlog record according to viewTime (the time the card was presented to the user), studyTime (the time to be counted towards total study time) and the ease of the card.
This is the functional bit of the scheduler: this is where cards are scheduled for review.
Card templates are rendered with
Mustache.js, with a custom escape
function to:
- render
[sound:<media filename>]as an audio tag - pass all other text unaltered (i.e. HTML is NOT escaped)
The templates are rendered with the note fields as context.
This is compatible with Anki templates for simple templates but only a small subset of Anki template features are supported.
Note: because field values are rendered without escaping, malicious decks may inject arbitrary content into the browser. Review the content of decks carefully before importing them.
Page templates are rendered with handlebars.
I might have used handlebars throughout but I have some templates with
spaces in the key names (e.g. {{Some Key}}): mustache supports this but
handlebars does not. It isn't obvious that this is an intentional feature
of mustache. I don't see an explicit test to ensure it works.
In Anki 2.1.20 or later on Windows, MacOS or iOS, or Linux with an add-on,
a field of the from {{tts en_US:Front}} will read the Front field in a
U.S. English voice.
A field of the from {{tts-voices:}} will produce a list of all supported voices. And various options can be given to specify the voice, speed, etc.
None of these are supported in srf.
The special fields {{tags}}, {{Type}}, {{Deck}}, {{Subdeck}},
{{Card}} are not supported in srf.
The special field {{FrontSide}} is supported in srf.
Fields of the form {{hint:MyField}} are not supported in srf.
Fields of the form {{text:Expression}} to strip HTML from the value are
not supported in srf.
Fields of the form {{type:Foreign Word}} are not supported in srf.
Sections bracketed by {{#FieldName}} and {{/FieldName}} do not work in
srf as in Anki.
In srf, the section will not be displayed if the field value is false or an empty list. If the value is a non-empty list, the section will be displayed once for each value in the list, with the list element as context for interpreting the field reference (i.e. the value should be a hash/object with an attribute matching the field reference). If the value is not a list and not false, the block will be rendered once with the value as context.
Cloze templates are not supported in srf.
In Anki, the implementation of template rendering is split between python
and rust. While the form of the templates appears to be much like Mustache,
and there is at least one comment in the code that refers to the {{ and
}} as mustaches, there does not appear to be an implementation of the
mustache templates included in the code, so the implementation is all
local. The rust code has comments that mention 'handlebars' but appears not
to use a handlebars package (crate or whatever the rust incantation is).
Anki Scripting: Automate your flashcards is from 2016. It doesn't mention the version of Anki investigated, but it is quite different from Anki in 2021. Correlating with tags in the Anki git repository, it would have been Anki 2.0.35 or earlier. There was a long break from 2.0.35 (2016) to the next tag 2.1.0 (2018). None the less, there is some good information here, including the comment: 'Anki uses a modified version of Pystache to provide Mustache-like syntax.' Indeed, Anki 2.0.34 included a copy of pystache, with files not modified for 7 to 9 years.
Anki 2.1.0 updated the pystache readme to:
Anki uses a modified version of Pystache to provide Mustache-like syntax.
Behaviour is a little different from standard Mustache:
- {{text}} returns text verbatim with no HTML escaping
- {{{text}}} does the same and exists for backwards compatibility
- partial rendering is disabled for security reasons
- certain keywords like 'cloze' are treated specially
This persisted until Anki 2.0.52 (8 Mar 2020) but was removed from Anki 2.1.21 (9 Mar 2020), which is about when I started using Anki. My oldest archive of the source is 2.1.16, Dec 22, 2019. 2.1 tags before 2.1.21 have been removed, it seems. Anyway, the template folder was still present in 2.1.16 but gone by 2.1.28, my next archive. This was the beginning of the pervasive changes, including the move to rust and fragmentation of the implementations of various features that put me off developing Anki addons or trying to improve the Anki scheduler. Quite an aside to templating, but template rendering is just one more feature that is now fragmented between python and rust code. And it seems no longer using anything like an external implementation of mustache: the current implementation maintains some of the syntax and semantics of mustache but the implementation is all local to Anki, since about Anki version 2.1.28.
The database is sqlite3.
There are six tables:
- card
- config
- dailystats
- fieldset
- revlog
- template
A card is the unit of study.
A card associates a fieldset (a set of field name/value pairs) with a template (mustache templates for the front and back of the card, and associated CSS) and a set of attributes used for scheduling the card.
The tuple (fieldsetid, templateid) should be unique. A unique index ensures this.
Fields:
- id
- fieldsetid
- templateid
- modified
- interval
- lastinterval
- due
- factor
- views
- lapses
- ord
The time (seconds since the epoch) when the card was last modified. Not used in scheduling. This is present for historical reasons - because it was kept in Anki.
This is the current scheduling interval: the time (seconds) from one review to the next. When a card is reviewed, a new interval is determined, based on how the card was rated (again, hard, good or easy) and the new interval is used to determine when the card is next due for review.
This is adjusted according to the difference between recent percent correct answers and the target for percent correct. It is a factor in calculation of the next interval for the card.
This field is badly named. It is the interval set when the card was reviewed, not adjusted in response to 'percent correct'. Better names would be unmodifiedinterval or originalinterval. Don't confuse this with lastinterval in revlog which is the interval from the last review.
When a card is reviewed, lastinterval is set to interval but interval might be adjusted before the card is reviewed again while lastinterval is not. It is always the interval when the card was last reviewed.
The lastinterval is copied to the lastinterval field of revlog.
This is the time (seconds since the epoch) when the card is due to be reviewed. This is the conclusion of the scheduling algorithm.
This should probably be called Ease Factor. It is a factor of the scheduling algorithm that reflects how easy the card is to remember. It is an exponentially weighted moving average of the card ratings (again, hard, good or easy) of past reviews.
This is a count of the number of times the card has been viewed. Not used in scheduling.
This is a count of how many times the card interval has changed from a value greater than the (arbitrary) 'mature threshold' to a value below it. Not used in scheduling.
This is used to sort new cards. When a new card is to be presented, the card with the lowest ord value is presented. If there are multiple, the selection is whichever the database driver returns first.
This table is a set of name/value pairs with their modification times (seconds since the epoch).
There are only two parameters: the database schema version and the 'correct factor' used in scheduling.
This is used to keep daily statistics, derived from revlog (see below).
The fields / statistics are:
- date
- cardviews - total number of reviews
- studytime - total minutes of study
- newcards - the number of new cards reviewed
- percentcorrect - the percent of 'correct' reviews
This table is updated after each review.
Missing historic data is added (e.g. after several days without study or if the dailystats table has been cleared) but there may be errors in the data produced for historic dates because the record of past data and changes is incomplete. In particular, there is no record of when cards are reset (i.e. interval reset to 0) or deleted (e.g. when fieldsets or templatesets are edited). Therefore, it is not possible to determine what cards existed or were in progress of being studied on a given day. All that is known is: what cards exist and have an interval > 0 currently and what cards were studied on a given day. This will not be problematic unless the dailystats table is cleared and all data is generated again from the revlog. In this case, counts of mature cards will tend to be a bit lower than actual for historic dates, due to subsequent card deletions and resets. Therefore, it is best not to clear the dailystats table.
A fieldset associates a set of field values with a templateset.
One card is produced for each template in the templateset.
Fields:
- id
- guid
- templateset
- fields
- ord
A guid from Anki import, used to identify matching records if the same card is imported again, in which case the field values or templateset might be different, so need to update the matching fieldset.
The name of the templateset this fieldset relates to. One card will be produced for each template in the templateset (i.e. for each template with the same templateset value).
The field values as a JSON serialization. Keys are field names and values are field values, which may be substituted into cards according to the templates in the template table.
For example:
{
"Audio":"[sound:喂你好.mp3]",
"Hanzi":"喂你好",
"Pinyin":"Wèi nǐ hǎo",
"English":"Hello? (on the telephone)"
}
For ordering the presentation of the cards. When a card is produced from the fieldset, the card's ord is set to the same as the fieldset's ord.
This only affects the order of presentation of new cards. Cards with lower ord are presented first.
On import from Anki, this is set to 10 * index where index is the index into the cards array. This should provide the same order of presentation as in Anki, except that each import begins with index 0 so cards will intermix.
A revlog record is produced each time a card is reviewed.
CREATE TABLE revlog (
id integer default (cast(ROUND((julianday('now') - 2440587.5)*86400000) as int)) not null,
revdate text default (strftime('%Y-%m-%d','now','localtime')) not null,
cardid integer not null,
ease text not null,
interval integer not null,
lastinterval integer not null,
factor real not null,
viewtime integer not null,
studytime integer not null,
lapses integer not null
)
- id: record create time, ms since epoch
- revdate: the date, localtime, of the review
- cardid: fk to card.id
- ease: the ease of the review: again, hard, good or easy
- interval: the new interval in seconds
- lastinterval: the previous interval in seconds
- factor: a factor for determining interval
- viewtime: the time spent viewing the card
- studytime: the time spent studying the card, for study time calculations
- lapses: the number of times the card has lapsed
The revdate field is redundant with id but it reduces processing time to produce statistics charts that are grouped by date, where the date is local timezone. Performing the conversion dynamically, per record, when the charts are produced adds significant time to the query or processing.
lastinterval is recorded to avoid having to do a lookup of the interval of the previous revlog for the card. It is used in determining if the card was new. It is also used in calculating percent correct.
A template record associates a templateset name with a pair of mustache templates for front and back of a card and some CSS for styling the card.
The set of templates with the same templateset value constitutes a templateset.
A card is linked to a template for rendering.
A fieldset and template both have attribute templateset. When a fieldset is saved, a card is produced for each template with matching templateset. If the templateset of a fieldset is changed, all the cards related to the old fieldset value are deleted and new card records are produced for each template in the new templateset.
Understanding details of the Anki database was essential to the initial implementation of srf: it used a slightly modified Anki database. Anki exports include a database that is similar but simpler than the database used by Anki itself, but some of these details are still helpful to interpreting the database in the export. The main advantage of the export is that all data serialization is to JSON rather than rust serde.
See Database Structure, which is a little more complete/correct.
This code parses some of the blobs in the Anki database. I could not find definition of how Anki/serde does this. The code was based on inspection of the blobs, trial and error. It may be that different database instances will code the data somewhat differently, or the field codes will change with each release of Anki. What I have here works for me, with the database from Anki 2.1.43.
Related data is stored in notes. For example, a question and answer.
A note has a type, which determines what fields may be populated (e.g. question and answer, or English and Chinese and pinyin).
A note type has a set of fields.
A note type has a set of card types/templates. The card types have front and back templates.
For each note, one card is produced for each card type associated with the note type of the note. The cards are associated with the note types by field ord.
The CSS for the cards is stored in notetypes.config. It isn't obvious from the card type editor, where it appears that each card type has front and back templates and 'styling'. The styling is common to all the card types of a given note type.
The database doesn't have a cardtypes table. Rather, the card types are manifest in the templates table. Each template is linked to a notetypes by templates.ntid. The relationship is many-to-one, with the different templates distinguished by ord, which is also in cards. The specific template for a card is determined by matching cards.ord to templates.ord.
Each templates record has two templates: front and back, serialized into templates.config.
Each note type is associated with a set of fields and a set of templates (a.k.a. card types).
Each note is associated with a note type which determines the fields and cards associated with the note. The fields are the attributes for which values may be saved. The templates determine how these are presented to the user. Each template has a front and a back layout (the 'flashcard').
This is a set of functions related to timing, including collection creation time, days since creation, day rollover time, offset from UTC, etc.
This defines v1_create_date which is the last 4:00 a.m. local time before the time the function was called.
This file contains SQL code to create the initial database, identified as Schema version 11. When a new database is created, this is the first set of tables, indexes, etc. created. Run from rslib/src/storage/sqlite.rs.
This is code for low level database operations on the Anki database. A key function is 'open_or_create_collection_db' which initializes the database connection and 'open_or_create' which opens the database and creates Anki tables as necessary according to the schema.
This defines upgrade_to_latest_schema and related constants (SCHEMA_MIN_VERSION, SCHEMA_STARTING_VERSION and SCHEMA_MAX_VERSION) but not the procedures for the actual upgrades.
Anki supports multiple database schemas, starting with schema 11. Presumably there were earlier schemas, but current code doesn't deal with them. When a new database is created, it begins as schema 11.
tables: col, notes, cards, revlog, graves.
Add tables: deck_config, config and tags
Deck configuration is moved from serialized data in col.dconf to the new deck_config table, one parameter per record, then col.dconf is cleared. Note that the configuration is still serialized data. There is one record per selectable deck configuration (deck type). My database has Default and Hard.
Tags are moved from col.tags to the new tags table, one tag per record, then col.tags is cleared.
Collection configuration is moved from col.conf to the new conf table, one parameter per record, then col.conf is cleared.
Add tables: fields, templates, notetypes, decks,
Note types are moved from col.models to the new notetypes, fields and templates tables, then col.models is cleared.
Decks are moved from col.decks to the new decks table, then col.decks is cleared.
Multiply deck initial ease * 100.
Divide initial ease of decks by 100 (revert change from Schema 15)
Change initial ease <= 1.3 to 2.5. and update cards with low eases.
Table col contains a single record with parameters of the entire collection.
create table col ( id integer primary key, crt integer not null, mod integer not null, scm integer not null, ver integer not null, dty integer not null, usn integer not null, ls integer not null, conf text not null, models text not null, decks text not null, dconf text not null, tags text not null );
Fields:
- id - always 1
- crt - collection creation time in seconds since the epoch
- mod - modification time in milliseconds
- scm - schema modification time
- ver - The database schema version
- dty - 0
- usn - 0
- ls - Last sync time in milliseconds
- conf - serialized collection configuration, before conf table, now ''
- models - serialized note types, before notetypes, now ''
- decks - Empty string
- dconf - serialized deck configuration, before deck_config, now ''
- tags - serialized tags before tags, now ''
In schema 11, crt is the last 4:00 a.m. local time before the actual creation time, as seconds since the epoch.
At database creation, scm is crt * 1000: that same 4:00 a.m. local time, but milliseconds since the epoch.
create table notes ( id integer primary key, guid text not null, mid integer not null, mod integer not null, usn integer not null, tags text not null, flds text not null, sfld integer not null, csum integer not null, flags integer not null, data text not null );
Fields:
- id - primary key
- guid - a GUID, probably used in syncing as id can't be consistent
- mid - fk to notetype.id
- mod - presumably epoch seconds of last modification time
- usn - ??? - always -1 in my database - to do with sync
- tags - Anki can add tags to cards, maybe notes too? Don't know how to tag a note Vs a card. - probably legacy
- flds - the field data, 0x1f as separator (escape???)
- sfld - something to do with searching and duplicates
- csum - some sort of checksum - some sort of sha1 digest
- flags - I guess notes can have flags too - probably legacy
- data - always empty - probably legacy
mid was model ID in Schema 11 but Schema 15 added table notetypes so now mid is fk to notetypes, but without a name change (it really should be ntid, or something like that).
create table cards ( id integer primary key, nid integer not null, did integer not null, ord integer not null, mod integer not null, usn integer not null, type integer not null, queue integer not null, due integer not null, ivl integer not null, factor integer not null, reps integer not null, lapses integer not null, left integer not null, odue integer not null, odid integer not null, flags integer not null, data text not null );
Fields:
- id - primary key
- nid - fk to notes
- did - fk to decks
- ord - order among cards linked to same note
- mod - card modification time
- usn - something to do with syncing in Anki
- type - 0: New, 1: Learn, 2: Review, 3: Relearn
- queue - the Anki queue
- due - when the card is due seconds since epoch or day number
- ivl - (renamed to interval) the interval between views
- factor - the factor for increasing the interval between views
- reps - number of times the card has been viewed
- lapses - number of times the card was 'repeat'
- left - something to do with (re)learn cards progress through steps
- odue - original due, for cards temporarily in a different deck
- odid - original deck ID, for cards temporarily in a different deck
- flags - ???
- data - ???
- seen - srf: milliseconds since epoch when card was last seen
- new_order - srf: integer for sorting new cards
The type seems to relate to how scheduling is done, at least in the version 2 scheduler. For example, there are distinct 'schedules' for learning and re-learning. These schedules are selected based on type, rather than queue.
In Anki, interval progresses through a series of values configured for new and relearning (lapses). These series of steps are configured in deck options: New Cards and Lapses tabs. A Lapsed card goes to relearn.
Getting a card seems to be based on queue, rather than type. But when a card is ansered, updating the interval seems to be based on type, not queue. The card type is also used when creating and deleting filtered decks.
srf records all times with units of milliseconds. This includes due and interval. New cards have interval = 0. When the card is seen, interval is set to the interval from the current time to when the card will next be due.
The relevant interval, when a card is seen, is the interval from when it was last seen to the time it was next seen. The card was last seen at cards.interval milliseconds before cards.due. The cards won't be shown before they are due but they might not be seen until some time after they are due - maybe hours or days after. That's OK. The actual interval is more relevant than any intended, theoretically ideal interval.
cards.new_order is for ordering the presentation of new cards. On import, it is set to whatever due was equal to. The separate field gives the advantage that the new card order isn't overwritten when the card is viewed. The deck can be reset, including the order of new cards. But, any cards viewed before import cannot be restored to their original new card order - the information is gone.
In Anki, review and 'day' learning cards have due set to a day number, with day 0 being the collection creation day, which is stored in the col table. In srf, day numbers aren't used. Due is always milliseconds since the epoch.
type is an integer.
type can be:
- 0=new,:
- 1=lrn,
- 2=rev,
- 3=relrn.
From consts.py:
# Card types
CARD_TYPE_NEW = 0
CARD_TYPE_LRN = 1
CARD_TYPE_REV = 2
CARD_TYPE_RELEARNING = 3
The card type determines aspects of how the cards are scheduled.
The card type is not completely orthogonal to the card queue. The relationship is obscure. Several of the decisions about scheduling are based on the queue, rather than the type. But others are based on type.
When a card is answered, the first decision: to treat it as a learning card or a review card, is based on queue. Many subsequent decisions are based on type.
There is different configuration for learning and relearning cares. In deck configuration, these are on tabs New Cards and Lapses. Each case has different sequence of steps. New cards have two settings for initial interval on graduation to review: Graduating interval and Easy interval. Relearning cards (lapses) only have New interval, which is a percentage of the previous interval.
If queue = QUEUE_TYPE_LRN or QUEUE_TYPE_DAY_LEARN_RELEARN, card is
rescheduled as a learning card: new or lapse according to type:
CARD_TYPE_REV and CARD_TYPE_RELEARNING are relearning, otherwise learning.
Relearning cards use settings from Lapse while learning cards use settings
from New Cards.
If type is CARD_TYPE_NEW, the card hasn't been seen before. On first view,
it is changed to CARD_TYPE_LRN and learning steps are initialized to the
first step from New cards configuration. This includes setting left.
If type is CARD_TYPE_REV or CARD_TYPE_RELEARNING, the card has lapsed.
Learning steps are from the Lapses configuration.
If type is CARD_TYPE_LRN, it progresses through the learning steps on Good,
until the last step, after which it is changes to CARD_TYPE_REV and ivl is
set to the Graduating interval. But on Easy, remaining learning steps are
skipped, type is changes to CARD_TYPE_REV and ivl is set to Easy
Interval.
queue is an integer.
queue can be:
- 0=new,
- 1=(re)lrn,
- 2=rev,
- 3=day (re)lrn,
- 4=preview,
- -1=suspended,
- -2=sibling buried,
- -3=manually buried.
From consts.py:
# Queue types
QUEUE_TYPE_MANUALLY_BURIED = -3
QUEUE_TYPE_SIBLING_BURIED = -2
QUEUE_TYPE_SUSPENDED = -1
QUEUE_TYPE_NEW = 0
QUEUE_TYPE_LRN = 1
QUEUE_TYPE_REV = 2
QUEUE_TYPE_DAY_LEARN_RELEARN = 3
QUEUE_TYPE_PREVIEW = 4
If queue is 1, due is epoch seconds and within the current day.
If queue is 3, due is day number, counting from collection creation day. This queue is used when the next (re)learning step is past the end of the day, in which case there is no provision for scheduling a time within the day. If one is studying near the end of the day, the next step may be one second beyon the end of the day or one second less than 24 hours beyond the end of the day and both cases are treated the same: the queue is set to 3 and card becomes due the next day. For example, the next steap may be 5 minutes (in the progression [1, 2, 5, 8, 10, 20] but if 5 minutes from now is past the end of the day, due becomes 'next day'.
due is an integer.
If type is 0 (new) then due is the note ID or some other value used to sort the new cards to order their presentation.
If type is 1 (learning) or 3 (relearning) then due is either epoch seconds or day number according to queue = 1 (learning) or 3 (day learning) respectively.
If type is 2 (review) then due is day number from collection creation day.
ivl is an integer.
ivl is the number of days between card reviews.
ivl is only relevant to review cards, which are scheduled according to the SRS scheduling algorithm. Learning and relearning cards are scheduled according to the steps in deck configuration for new and lapses: ivl is irrelevant.
For a card that has never been reviewed (i.e. new or learning), ivl will be 0.
Once a card has progressed to the review queue, ivl will be set to the interval in days. If it lapses, ivl is reduced by a configurable amount so that after completing the lapse/relearning steps, it graduates with a lesser interval. On graduation, the interval is what it was set to on lapse, or one more than this if it graduated early by 'Easy'.
Initially, ivl is 0. It is set to the configurable graduating interval or Easy interval when a card graduates from learning to review, according to whether ease was Good or Easy. By default, Graduating interval is 1 day and Easy interval is 4 days.
left is an integer value.
If type is 1 (CARD_TYPE_LRN) then left is initially set to the number of learning steps (per deck configuration for new cards) + 1000 * the number of steps that could be completed before the end of the day. The latter depends on the current time, when the end of the day is and the size of each step.
left = X + Y * 1000, where X is the number of learning steps still to be completed (i.e. it is an index into the array of learning steps, but from the end of the array instead of the beginning) and Y is the number of steps that can be completed in the same day, at the time the card was scheduled, given current time, time of end of day and the size of the remaining steps to be completed.
As the card progresses through the learning steps, X is decremented and Y is updated according to the time and step sizes.
create table revlog ( id integer primary key, cid integer not null, usn integer not null, ease integer not null, ivl integer not null, lastIvl integer not null, factor integer not null, time integer not null, type integer not null );
integer
epoch milliseconds.
integer
fk to cards.id
integer
Something to do with syncing. -1 by default.
integer
The button that was clicked on review 1, 2, 3 or 4 for Fail, Hard, Good or Easy.
integer
Negative value is seconds. Positive value is days since collection creation day.
integer
The factor for adjusting interval. 0 for non-review cards. This is 1000 times that multiplier (i.e. the new interval is the old interval * factor / 1000)
integer
Milliseconds spent viewing the card.
integer
Always 0???
create table graves ( usn integer not null, oid integer not null, type integer not null );
CREATE TABLE "fields" ( "ntid" integer NOT NULL, "ord" integer NOT NULL, "name" text NOT NULL, "config" blob NOT NULL, PRIMARY KEY("ntid","ord") ) WITHOUT ROWID;
ntid: fk to notetypes ord: ordinal for sorting fields name: the field name config: not used in srf.
The config field holds a serialized data structure (rust/serde) that appears to relate to the Anki field content editor: sticky, rtl (right-to-left), font_name, font_size and 'other' for a JSON string, I think.
From rslib/backend.proto:
message NoteFieldConfig {
bool sticky = 1;
bool rtl = 2;
string font_name = 3;
uint32 font_size = 4;
bytes other = 255;
}
If sticky is true, then the input is not cleared on save when entering notes. Default is false.
If rtl is true then the field text is right-to-left. Default is false.
Font name and size are for the Anki note editor. This doesn't affect display of the note/cards. Default is Arial, 20.
Other is unknown. All I see is {"media":[]}.
srf uses ntid, ord and name, at least until I add a card/note editor.
Note that this table only holds field names and sort order. The values are in the notes table: notes.flds, with all field values serialized into the single field.
- id - primary key
- name - text name of notetype
- mtime_secs - modification time
- usn - ???
- config - serialized data structure
Note types are identified by ID. Fields and notes are linked to this ID.
mtime_secs is used in Anki sync, to find note types modified since last sync, presumably. I haven't looked into sync.
usn is used in Anki sync.
config - this is a rust/serde serialized data structure. See importdb.js
config:
- kind: 0 - Normal, 1 - Cloze
- sort_field_idx:
- css: the css for the notes
- target_deck_id: ???
- latex_pre
- latex_post
- latex_svg
- reqs: an array ???
- other: arbitrary JSON serialized data
The css for the cards is here. This makes it common to all the templates related to the note type. In srf, the css is extracted and added to the templates table. In srf, each template has its own CSS.
Anki has support for using LaTeX to format cards. The latex_* fields relate to this.
CREATE TABLE "templates" ( "ntid" integer NOT NULL, "ord" integer NOT NULL, "name" text NOT NULL, "mtime_secs" integer NOT NULL, "usn" integer NOT NULL, "config" blob NOT NULL, "front" text NOT NULL DEFAULT '', "back" text NOT NULL DEFAULT '', "css" text NOT NULL DEFAULT '', PRIMARY KEY("ntid","ord") ) WITHOUT ROWID;
I added front, back and css. In Anki the HTML for front and back are serialized into templates.config and the css is serialized into notetype.config. The downside of this being that the CSS is common to all card types associated with a given note type. Not a big issue, but with the CSS moved to the templates table, each template can have its own CSS.
From templates.rs:
CardTemplate {
ord: None,
name: name.into(),
mtime_secs: TimestampSecs(0),
usn: Usn(0),
config: CardTemplateConfig {
q_format: qfmt.into(),
a_format: afmt.into(),
q_format_browser: "".into(),
a_format_browser: "".into(),
target_deck_id: 0,
browser_font_name: "".into(),
browser_font_size: 0,
other: vec![],
},
}
These files contain the transferrable state of an Anki collection: a set of decks containing templates, notes, cards and revision logs.
One could examine the Anki source code to determine what is in an export from this source but the code is complex with multiple languages and tools to interface them that obscure the interactions unless is familiar with them.
I haven't reviewed the Anki source code for a long time. Here are merely my notes and observations, not rooted in an understanding of the Anki source code.
The zip file contains:
- one or more sqlite database files, named
collectionwith different extensions depening on version (see below). - media files
Media files (audio, images, etc.) are named numerically, from 0.
There is a file named media which contains JSON serialization of a map of
these numeric filenames to filenames.
For example:
{
"0": "audio1-2exercise3.mp3",
"1": "audio1-1exercise2.mp3",
"2": "audio1-2exercise4.mp3"
}
There is no record of mime type. The file type can be deduced from the filename extension or by inspection of the file data.
The zip file will contain one or more sqlite database files, all named
collection but with different extensions for different versions of Anki.
There is often only one sqlite databases but occasionally there are multiple, allowing the collection to be imported to multiple versions of Anki.
This is for versions of Anki before 2.0. I have not seen an example of this.
I haven't searched exhaustively but all the shared decks on
ankiweb have collection.anki2 or
collection.anki21 - even those with modification dates back to 2012,
which seems to be about the oldest.
The old format isn't important. Anki 2.0 has been around since at least 2013. The oldest tag on the Anki repository is 2.0.4 from 8 Jan 2013.
The database schema is the same for these, so the difference must be in the contained values or their interpretation.
This is for versions of Anki from 2.0 but less than 2.1.
Tables:
- cards
- col
- graves
- notes
- revlog
- sqlite_stat1
- sqlite_stat4
sqlite> .schema cards
CREATE TABLE cards (
id integer PRIMARY KEY,
nid integer NOT NULL,
did integer NOT NULL,
ord integer NOT NULL,
mod integer NOT NULL,
usn integer NOT NULL,
type integer NOT NULL,
queue integer NOT NULL,
due integer NOT NULL,
ivl integer NOT NULL,
factor integer NOT NULL,
reps integer NOT NULL,
lapses integer NOT NULL,
left integer NOT NULL,
odue integer NOT NULL,
odid integer NOT NULL,
flags integer NOT NULL,
data text NOT NULL
);
CREATE INDEX ix_cards_usn ON cards (usn);
CREATE INDEX ix_cards_nid ON cards (nid);
CREATE INDEX ix_cards_sched ON cards (did, queue, due);
sqlite> .schema col
CREATE TABLE col (
id integer PRIMARY KEY,
crt integer NOT NULL,
mod integer NOT NULL,
scm integer NOT NULL,
ver integer NOT NULL,
dty integer NOT NULL,
usn integer NOT NULL,
ls integer NOT NULL,
conf text NOT NULL,
models text NOT NULL,
decks text NOT NULL,
dconf text NOT NULL,
tags text NOT NULL
);
- id: there is only one record, with ID = 1
- crt: record creation time
- mod: record modification time
- scm: schema modification time - maybe the database schema
- ver: version - maybe the database schema version
- dty: dirty ankisyn2 says this is unused.
- usn: update sequence number - relates to syncing.
- ls: last sync time
- conf: JSON serialization of configuration options that are synced
- models: JSON serialization of the models
- decks: JSON serialization of the deck(s)
- dconf: JSON serialization of deck options
- tags: tags used in the collection
Basic Anki configuration option settins.
An example from a collection.anki21 database
{
"timeLim":0,
"nextPos":9401,
"dueCounts":true,
"sortType":"noteFld",
"localOffset":-720,
"schedVer":2,
"estTimes":true,
"sortBackwards":false,
"newSpread":0,
"dayLearnFirst":false,
"rollover":4,
"collapseTime":1200,
"creationOffset":-720,
"addToCur":true,
"activeDecks":[1629058964075],
"curDeck":1629058964075,
"curModel":1409030500500
}
An example from a collection.anki2 database (sorted for consistency with above)
{
"timeLim":0,
"nextPos":2,
"dueCounts":true,
"sortType":"noteFld",
"localOffset":-720,
"schedVer":1,
"estTimes":true,
"sortBackwards":false,
"newSpread":0,
"dayLearnFirst":false,
"collapseTime":1200,
"addToCur":true,
"activeDecks":[1],
"curDeck":1,
"curModel":1629059140118,
}
So, anki21 has these additional values:
- rollover
- creationOffset
From my recollection of early work with Anki 2.0 then Anki 2.1, where I had problems with the buggy timezone handling and rollover from day to day, I think these are:
rollover: The time of day, local time zone, when the Anki 'day' rolls over. Anki keeps track of longer times in terms of days, not seconds or milliseconds. The day number is the number of days since the initialization of the collection. The creation time is in col.crt. This setting will affect various statistics and the interpretation of times specified as a number of days Vs the local time.
creationOffset: I'm not so sure about this but I expect that this is the timezone offset when the collection was created. Different users can be in different time zones so this might affect how times are recorded. My recollection is that times are recorded in local time not UTC. This was problematic because at transition between daylight saving and standard time, some calculations were incorrect. I submitted patches for some of these errors, some of which were accepted, others modified or rejected. Damien was concerned about impact of change on existing users, and chose not to fix all bugs therefore.
So, Anki 2.1 deals with dates and times a bit differently and includes these parameters not present in Anki 2.0. Time related fields (e.g. in card and revlog) are likely to be interpreted differently even if, superficially they look the same. But this will only affect study history and due dates. The cards themselves (notes, templates, etc.) do not depend on time of day.
An example from a collection.anki2 database:
{
"1629059140120": {
"id": 1629059140120,
"name": "Basic (optional reversed card)",
"type": 0,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
},
{
"name": "Card 2",
"ord": 1,
"qfmt": "{{#Add Reverse}}{{Back}}{{/Add Reverse}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Front}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Add Reverse",
"ord": 2,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
],
[
1,
"all",
[
1,
2
]
]
]
},
"1629059140118": {
"id": 1629059140118,
"name": "Basic",
"type": 0,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
]
]
},
"1629059140119": {
"id": 1629059140119,
"name": "Basic (and reversed card)",
"type": 0,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
},
{
"name": "Card 2",
"ord": 1,
"qfmt": "{{Back}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Front}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
],
[
1,
"any",
[
1
]
]
]
},
"1629059140121": {
"id": 1629059140121,
"name": "Basic (type in the answer)",
"type": 0,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}\n\n{{type:Back}}",
"afmt": "{{Front}}\n\n<hr id=answer>\n\n{{type:Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0,
1
]
]
]
},
"1629059140122": {
"id": 1629059140122,
"name": "Cloze",
"type": 1,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Cloze",
"ord": 0,
"qfmt": "{{cloze:Text}}",
"afmt": "{{cloze:Text}}<br>\n{{Back Extra}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Text",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back Extra",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n\n.cloze {\n font-weight: bold;\n color: blue;\n}\n.nightMode .cloze {\n color: lightblue;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
]
]
}
}
So, this is a 'map' of models, keyed by model ID (mid).
type: I have a vague recollection that this is 0 or 1. 1 for models that
support closures or 0 otherwise. But I don't recall where I got that
impression. const.py in the source has MODEL_STD = 0 and MODEL_CLOZE = 1.
I have seen MODEL_STD compared to type, so these must be the values. But no
explanation of what they are. If type is not MODEL_STD, one always gets the
first template. Evidently, cloze models don't allow multiple templates.
mod: modification timestamp
usn: 'Update Sequence Number'? Fields with this name are scattered throughtout the database. It relates to synchronization.
sortf: ???
did: deck ID. I have a vague recollection that this is the default deck of cards/notes added with this model.
tmpls: an array of templates. A model might have many templates. A separate card is generated for each template.
tmmpls.ord: ordinal, for controlling the order of the templates.
tmpls.bqfmt: In the source, in one place, bqfmt is mapped to q_format_browser.
'q' is for 'question' (and 'a' is for 'answer'). It seems 'b' is for
browser. There is some code under a comment # legacy defining function
templates_for_card that takes a boolean browser. If browser is true,
the bqfmt and bafmt templates are used. If browser is not true or if bqfmt
or bafmt don't exist, then qfmt and afmt are used. So, it seems that bafrt
and bqfmt are templates that can override qftm and afmt in the context of a
browser but doing to is a legacy feature. Maybe, long ago, the templates
could be rendered in a browser or in other contexts???
tmpls.did: This must be deck ID again, but why would an individual template be associated with a particular deck?
tmpls.bfont and tmpls.bsize: I am guessing that again 'b' relates to browser. These probably allow different font and font size in a browser.
This is an example from a collection.ank21 database:
{
"1409030500500": {
"id": 1409030500500,
"name": "Basic (optional reversed card)-62f40",
"type": 0,
"mod": 1410892824,
"usn": -1,
"sortf": 0,
"did": 1410882881255,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "Arial",
"bsize": 12
},
{
"name": "Card 2",
"ord": 1,
"qfmt": "{{#Add Reverse}}{{Back}}{{/Add Reverse}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Front}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "Arial",
"bsize": 12
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20,
"media": []
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20,
"media": []
},
{
"name": "Add Reverse",
"ord": 2,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20,
"media": []
}
],
"css": ".card {\n font-familiy: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
],
[
1,
"all",
[
1,
2
]
]
],
"tags": [
"chinese-w01-l02"
],
"vers": []
},
"1629058828334": {
"id": 1629058828334,
"name": "Basic",
"type": 0,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
]
]
},
"1629058828338": {
"id": 1629058828338,
"name": "Cloze",
"type": 1,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Cloze",
"ord": 0,
"qfmt": "{{cloze:Text}}",
"afmt": "{{cloze:Text}}<br>\n{{Back Extra}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Text",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back Extra",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n\n.cloze {\n font-weight: bold;\n color: blue;\n}\n.nightMode .cloze {\n color: lightblue;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
]
]
},
"1629058828335": {
"id": 1629058828335,
"name": "Basic (and reversed card)",
"type": 0,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
},
{
"name": "Card 2",
"ord": 1,
"qfmt": "{{Back}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Front}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
],
[
1,
"any",
[
1
]
]
]
},
"1629058828337": {
"id": 1629058828337,
"name": "Basic (type in the answer)",
"type": 0,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}\n\n{{type:Back}}",
"afmt": "{{Front}}\n\n<hr id=answer>\n\n{{type:Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0,
1
]
]
]
},
"1629058828336": {
"id": 1629058828336,
"name": "Basic (optional reversed card)",
"type": 0,
"mod": 0,
"usn": 0,
"sortf": 0,
"did": 1,
"tmpls": [
{
"name": "Card 1",
"ord": 0,
"qfmt": "{{Front}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Back}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
},
{
"name": "Card 2",
"ord": 1,
"qfmt": "{{#Add Reverse}}{{Back}}{{/Add Reverse}}",
"afmt": "{{FrontSide}}\n\n<hr id=answer>\n\n{{Front}}",
"bqfmt": "",
"bafmt": "",
"did": null,
"bfont": "",
"bsize": 0
}
],
"flds": [
{
"name": "Front",
"ord": 0,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Back",
"ord": 1,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
},
{
"name": "Add Reverse",
"ord": 2,
"sticky": false,
"rtl": false,
"font": "Arial",
"size": 20
}
],
"css": ".card {\n font-family: arial;\n font-size: 20px;\n text-align: center;\n color: black;\n background-color: white;\n}\n",
"latexPre": "\\documentclass[12pt]{article}\n\\special{papersize=3in,5in}\n\\usepackage[utf8]{inputenc}\n\\usepackage{amssymb,amsmath}\n\\pagestyle{empty}\n\\setlength{\\parindent}{0in}\n\\begin{document}\n",
"latexPost": "\\end{document}",
"latexsvg": false,
"req": [
[
0,
"any",
[
0
]
],
[
1,
"all",
[
1,
2
]
]
]
}
}
This has added flds.media, but only in the first model. The others don't
have it. It is an empty array in all the cases I have seen.
Otherwise, this looks about the same as in anki2.
An example from a collection.anki2 database:
{
"1": {
"id": 1,
"mod": 0,
"name": "Default",
"usn": 0,
"lrnToday": [ 0, 0 ],
"revToday": [ 0, 0 ],
"newToday": [ 0, 0 ],
"timeToday": [ 0, 0 ],
"collapsed": true,
"browserCollapsed": true,
"desc": "",
"dyn": 0,
"conf": 1,
"extendNew": 0,
"extendRev": 0
}
}
An example from a collection.anki21 database:
{
"1629058964075":{
"id":1629058964075,
"mod":1629059039,
"name":"Coursera - Chinese for Beginners",
"usn":-1,
"lrnToday":[0,0],
"revToday":[0,0],
"newToday":[0,5],
"timeToday":[0,44860],
"collapsed":true,
"browserCollapsed":true,
"desc":"Please see the <a href='https://ankiweb.net/shared/info/'>shared deck page</a> for more info.",
"dyn":0,
"conf":1,
"extendNew":0,
"extendRev":0
},
"1":{
"id":1,
"mod":0,
"name":"Default",
"usn":0,
"lrnToday":[0,0],
"revToday":[0,0],
"newToday":[0,0],
"timeToday":[0,0],
"collapsed":true,
"browserCollapsed":true,
"desc":"",
"dyn":0,
"conf":1,
"extendNew":0,
"extendRev":0
}
}
These appear to be the same structure.
Keyed by deck ID (did).
mod: modification time.
name: the name of the deck
usn: Update Sequence Number - to do with synchronization
lrnToday: counts of reviews of learning cards
revToday: counts of reviews of non-learning cards
newToday: counts of new cards
timeToday: study time today
collapsed: I think true if the deck is collapsed in the deck browser
browserCollapsed: ???
desc: probably a description
dyn: probably whether the deck is dynamic
conf: ???
extendNew: ??? - maybe for adjusting the number of new cards?
extendRev: ??? - maybe for adjusting the number of review cards?
An example from a collection.anki2 database:
{
"1": {
"id": 1,
"mod": 0,
"name": "Default",
"usn": 0,
"maxTaken": 60,
"autoplay": true,
"timer": 0,
"replayq": true,
"new": {
"bury": false,
"delays": [
1,
10
],
"initialFactor": 2500,
"ints": [
1,
4,
0
],
"order": 1,
"perDay": 20
},
"rev": {
"bury": false,
"ease4": 1.3,
"ivlFct": 1,
"maxIvl": 36500,
"perDay": 200,
"hardFactor": 1.2
},
"lapse": {
"delays": [
10
],
"leechAction": 1,
"leechFails": 8,
"minInt": 1,
"mult": 0
},
"dyn": false,
"newMix": 0,
"newPerDayMinimum": 0,
"interdayLearningMix": 0,
"reviewOrder": 0
}
}
This is a serialization of the deck configuration. Very specific to the workings of the Anki scheduler.
I haven't seen an example with anything in this table.
sqlite> .schema graves
CREATE TABLE graves (
usn integer NOT NULL,
oid integer NOT NULL,
type integer NOT NULL
);
qlite> .schema notes
CREATE TABLE notes (
id integer PRIMARY KEY,
guid text NOT NULL,
mid integer NOT NULL,
mod integer NOT NULL,
usn integer NOT NULL,
tags text NOT NULL,
flds text NOT NULL,
-- The use of type integer for sfld is deliberate, because it means that integer values in this
-- field will sort numerically.
sfld integer NOT NULL,
csum integer NOT NULL,
flags integer NOT NULL,
data text NOT NULL
);
CREATE INDEX ix_notes_usn ON notes (usn);
CREATE INDEX ix_notes_csum ON notes (csum);
sqlite> .schema revlog
CREATE TABLE revlog (
id integer PRIMARY KEY,
cid integer NOT NULL,
usn integer NOT NULL,
ease integer NOT NULL,
ivl integer NOT NULL,
lastIvl integer NOT NULL,
factor integer NOT NULL,
time integer NOT NULL,
type integer NOT NULL
);
CREATE INDEX ix_revlog_usn ON revlog (usn);
CREATE INDEX ix_revlog_cid ON revlog (cid);
I have tried chart.js. It's quite simple for a basic chart.
Consider also d3.js
Highcharts is easy to use. But it requires a license. CC for non-commercial, but it's not like FOSS.
https://alternativeto.net/software/highcharts/?license=free
plotly is open source under MIT license, available on GitHub and js available from CDN. It is even easier to use than Highcharts (at least, less verbose) and makes good looking charts with download, zoom, pan, values on hover and all sorts. Seems quite awesome.
The server runs on NodeJS
Dealing with file system. I haven't tried this on Windows. It probably doesn't handle paths in a Windows compatible way, but it shouldn't take too much work to make it compatible. It doesn't deal with files too much. On the other hand, it's not a priority for me: I don't use Windows unless I have to.
For some timezone and time data processing.
For generating UUID/GUID.
For command line argument processing. I tried a few. This one is simple and adequate.
For parsing config file, which is JSON, but with support for comments.
The is the web server framework. It handles parsing and routing of requests and production of responses.
To serve a favicon.
This is template middleware for express. The website pages are generated from handlebars templates.
For dealing with form fields.
Another template engine. This one is, by default, a bit more compatible with the Anki templates. So, the Anki templates are processed by Mustache and the web pages are then produced from Handlebars templates. Handlebars documentation says that it is compatible with Mustache, so perhaps there is a way to consolidate on just Handlebars, in which case Mustache can be dropped.
For unzipping Anki export files.
Interface to the SQLite database
Some script for making tables sortable. A copy of the script is in the root directory of the project, for the moment, but not used.
This is another script for generating sortable tables. This takes quite a different approach to sorttable. It seems well documented, but I haven't tried it yet.
This is some guidance and examples of sorting a table.
Yet another flashcard program, because I am too stupid, lazy and stubborn to find and adapt to an existing one (there are many).
I used Anki desktop for a couple of years. It is quite good, with many decks available and a good feature set. But there were bugs in timezone handling that affected me and I wanted a somewhat different scheduler with automatic adjustment of new cards per day to maintain a more constant workload. I submitted patches and created add-ons to fix bugs and add some of the features I wanted, but I became increasingly frustrated by the complexity of the build environment, the frequency of changes to the scheduler api and internals, lack of documentation of the internals and add-on APIs, the inscrutable rust back end and blobs in the database. Eventually I decided it would be less work to write my own (I only need and use a small subset of Anki features) than to keep struggling with Anki. I have much respect and appreciation for Anki, but I want something a little different in the scheduler and to spend more time using the tool and less time developing and maintaining it.
I just spent all my free time (and a lot of time that really wasn't free, and I should have been doing other things) for a couple of weeks, to adapt my Anki scheduling add-on to more recent versions of Anki and, in particular, to the shift of scheduling function to the back-end and elimination of the hooks I had been using. While the outcome was some improvement in the approach (necessity is the mother of invention, as they say) overall the cost/benefit was not good.
It took me only three days to get this to the point I could get back to studying - significantly less time than the last iteration of my Anki add-ons, and I still didn't have the scheduling I actually wanted in Anki. It has taken considerably longer to bring it to its current state, and it still needs a lot of work, but it is good enough for my immediate needs.
I'm not the only one frustrated by Anki and writing an alternative. See Where Anki falls short
With this, I can do whatever I want with scheduling. I like the srf scheduler much more than the Anki scheduler, old or new. In particular, a backlog of cards is relatively easy to work through. This is because of the prioritization of cards with shorter intervals and not showing any new cards while the backlog persists. With the Anki scheduler, I became overwhelmed and was no longer learning anything effectively, even with new cards totally disabled. With the srf scheduler, this doesn't happen. Even with a large backlog, I am able to learn and work through the backlog. It is a much nicer experience.
The biggest challenges were reverse engineering the serialization of the blobs in the database: because after hours of searching I still couldn't find a definition of the rust/serde serialization. It's open source. I'm sure the information is there somewhere, but it's not documented, not discussed, and there are too many layers of abstraction and build automation on top of it - I couldn't find the code. The other issue was the collation function in the rust sqlite driver. It is rust specific. I found the implementation but didn't want to re-implement it in JavaScript - I don't need it. But I couldn't decide this until I found what it was. Once I had determined I didn't need or want it, it only took me a little while to learn how to remove it from the database.
Subsequently, I have abandoned conversion of the Anki database. I have written an import from an Anki export. The Anki export is similar to the Anki database, but all the serialized data is JSON, which is much easier to work with.
- Pure JavaScript on Node
- Browser based
- No runtime dependencies - works offline
- Simple scheduler without the complexity of Anki queues or decks
- Simple SQLite3 database
- No obscure collation function in the database
- Import from Anki deck exports
- Very little for configuration - need to edit the code for most changes
- No reports - just rudimentary stats to the browser or server console
- No decks, tags or flags - just one pool of cards
- Only simple text fields and media
- No synchronization between devices / databases
Anki uses Again as worst case ease name.
I changed it to Fail which seems more consistent with Hard, Good and Easy, gramatically, but it is quite negative. Is there a better term?
I went through a list of four letter words and here are some possible alternatives: Fail, Miss, Skip, Grim, Cold, Nope, Next, Pass, Loss, Wash, Gone, Balk, Bane, Blur, Dire, Lost
Of these, I like Fail and Pass most. There are games / contests where Pass is used to indicate that you are failing so badly that you don't want to waste time - just move on to the next item.
Hard, Good and Easy are adjectives. Neither Fail nor Pass are. They are both intrasitive verbs.
What is the adjective that means harder than hard?
We have Good, so maybe Bad, but that's also very negative.
Bad, Worse, Worst.
Harder? Hardest?
Maybe Lost is good. It is an adjective. Lapsed has similar meaning and is used to describe a card that was known but is now forgotten.
Gone has similar sense as Lapsed. Gone from memory / recollection.
Elusive?
I want something like Fleeting, Elusive, Lost, Gone.
Maybe Gone is good. Gone from memory. It is an adjective.
Forgotten, but a shorter word.
Lost?
Add commandline option htdocs and support for an htdocs directory to override the static content built into the srf server.
Add commandline option views and support for a views directory to override the handlebars templates built into the web server.
Remove templateset.fields - it is redundant with the actual fields in the templates of the templateset.
Remove fieldsets table entirely. Add fieldset.ord
Add support for import of CSV files for templates and fieldsets.
Remove the distinction between imports of anki2 and anki21 apkg files. For the purposes of import to srf, they are the same.
README changes
README changes.
Ensure when editing that a fieldset includes all fields in the templateset.
On import, set card factor to 2.
- README changes
- LICENSE
- Remove old cruft
- Daily database backup
- Fix calculation of last interval
- Change config.maxNewCards to config.newCardLimit
- Add config.newCardMinPercentCorrect
Update dependencies
Update dependencies
Changed the scheduling algorith again. Changed Fail and Hard to have maximum intervals instead of minimum intervals and changed the default again factor to 0.3.
Change default again factor to 0.5 and hard factor to 0.8.
Eliminate the correct factor.
Add adjustment of interval and due date of learning and mature cards, according to the difference between Percent Correct and percentCorrectTarget.
Tune down the ease weights.
Change card stages to:
- 0 / unseen / unconcious incompetence / UI
- 1 / new / concious incompetence / CI
- 2 / learning / concious competence / CC
- 3 / mature / unconcious competence / UC
- 4 / mastered / mastery / M
Change stats charts to by date instead of day#
Add revdate to revlog to improve performance of generating charts.
Improve performance of rendering charts on stats page
Add table dailystats and re-implement generation of daily stats charts to get data from dailystats.
Removed the old getChart methods and added getChartsDailyStats.
Delete all records from dailystats after an Anki package import, which may include revlog entries for the imported deck(s). This will force the stats to be recalculated, including the new revlog entries.
Add card.lastinterval
Database schema 11
Reorder changes
Add a minimum count of mature cards in the percent correct window at which percent correct is calculated.
Add 'if exists' to all 'drop index' statements.
Fix import test
Add chart of percent correct
Update dependencies
- Add Admin page
- Move links to templates, template sets and field sets to the admin page
- Add config page - read only view of configuration
- Add link to config page to the admin page
- Review calculation of percent correct: upper bound to config.maxInterval
- Fix fixRevlogInterval to get card interval from card.lastinterval (the unadjusted interval) rather than card.interval (the adjusted interval).
- Add a plot of unadjusted interval to Cards per interval.
- Fix adjustCards to complete before next due is determined
- Fix logging reviews of new cards
- Add options --port
- Fix update of daily stats new card count
- Minimum interval of 1 second
- Change dailystats.studyminutes to dailystats.studytime
- Improve calculation of average study time per day
- Fix calculation of estimated study time
- Provide feedback on why new cards are not presented
- Fix getAverageStudyTime
- Update dependencies
- Fix new card time limit
- Make minimum interval between new cards = studyTimeLimit / newCardLimit
- Simplify regulation of new cards
- Revise home and stats pages
- Add new cards remaining below traffic lights
- Fix legend position on Cards per interval
- Add title to signal stats
- Show new card limit instead of new cards remaining on home and stats pages Decrease sensitivity to average study time to range 90% to 110%
- Eliminate quantization and dispersion of due
- Change estimation of upcoming study time
- Change estimate of average study time
- Fix interval between new cards
- Fix selection of new cards - ignore card.due
- Enhance selection of new cards - avoid cards from recently viewed fieldsets
- Don't show new cards if there is a backlog
- Don't show new cards if study time past 24 hours > config.studyTimeLimit
- Change default minimum time between related cards to 1 hour
- Don't show new cards if study time next 24 hours > config.studyTimeLimit
- Avoid showing a card too soon after another of the same fieldset
- Update dependencies
- Fix intervals between new cards
- Change determination of mode
- Change default action on home and back pages, per mode
- Change home Study button to get a new card if nothing due.
- Parameterize calculation of current new card limit
- Change button colours to highlight default action
- Update dependencies
- Add option to sort due cards by due instead of interval.
- Simplify regulation of new cards
- README changes.
- Update the help file.
- Change Break button to Stop on the back of cards.
- Further simplify regulation of new cards
- Change 'Again' button to 'Fail'
- Remove the New Card button from the home page
- Improve calculation of average study time
- Change the scheduler to present new cards until study time is the average of config.minStudyTime and config.maxStudyTime.
- Add getAveragePercentCorrect based on dailystats
- Update the README.
- Fix revlog for change of ease from Again to Fail
- Fix date range for calculation of percent correct
- Introduce config.targetStudyTime
- Remove config.maxStudyTime
- Change the scheduler to present new cards until study time is config.targetStudyTime
- Change the scheduler to remove the upper limit on study time
- Remove the scheduler code to a separate package: @ig3/srf-scheduler
- Improve calculation of average time per card for Study Time per Hour chart
- set traffic lights based on scheduler getNewCardMode
- Reimplement calculation of average new cards per day
- Update dependencies
- Update dependencies
- Average study time over 14 days for home page
- Get average study time from revlog instead of dailystats
- Update dependencies - @ig3/srf-scheduler
- Add new card stats to stats page
- Update dependencies - @ig3/srf-scheduler
- Add new cards to top right of home, front and back pages
- Exclude current day from calculation of average new cards per day
- Set revdate from id and timezone when fixing database
- Show short term average study time
- Remove fieldset ID from front and back views
- Add countdown to next new card to home, front and back pages
- Average study time over a longer period
- Show reviews to next new card
- Catch signals for orderly shutdown
- Update dependencies
- Update dependencies
- Update plotly
- Revise plot layouts
- Fix hover text on home page plot
- Add time since last review to front and back
- Update dependencies
- Update dependencies
- Move various functions from bin/cmd.js to the library
- Allow scheduler to be provided as an option
- Make scheduler an instance variable
- Revise stats page
- Reorder the card metrics before the buttons on front and back of cards
- Revise home page layout
- Update dependencies
- Change calculation of mature cards for daily stats
- Fix getCountCardsStage4 to count cards with interval > maxInterval
- Fix getCountCardsStage0 to count cards with interval < 0
- Reduce goodMinInterval to 2 minutes
- Remove dependency getopts in favour of node utils.parseArgs
- Update dependencies
- Add command line argument to specify the scheduler plugin
- Change test package to @ig3/test
- Change CSS for buttons, for more consistent font and font-size
- Add graph of interval and factor to card back page
- Drop the Matured & Lapsed chart and related data
- Add chart of cards by stage
- Update dailystats at each card review
- Enhance fix to add missing dailystats counts of cards by stage
- Don't average percent correct
- Record current percent correct in dailystats
- Change card history graph interpolation style