Flask Web Application Development

Environments

• Development Environment: notebooks.ai
• Production Environment: pythonanywhere.com
  • wcj365.pythonanywhere.com
• Source Code Repository: GitHub (this repo)

Components

• Flask
• sqlite3
• flask_sqlalchemy

References:

• https://hackersandslackers.com/author/todd/
• https://hackersandslackers.com/series/building-flask-apps/
• https://www.cs.rochester.edu/u/bdicken3/csc210/
• https://www.cs.rochester.edu/u/bdicken3/csc210/slides/Lecture_07_Introduction_to_Flask.pdf
• http://zetcode.com/python/flask/
• https://www.twilio.com/blog/how-run-flask-application
• https://smallbusiness.chron.com/use-sqlite-ubuntu-46774.html
• https://help.pythonanywhere.com/pages/Flask/

Steps

1. To install flask

$pip install -U Flask

2. To install -U flask_sqlalchemy

• $pip install -U flask_sqlalchemy
• "-U" = "--updates"

3. To combine 1 and 2 into a single requirements.txt file The requirements.txt file contains two simple lines:

flask
flask_sqlapchemy

$install -r requirements.txt

4. to Run flask

• $export FLASK_APP="/app/webapps/hello/hello.py"

• $flask run

sqlite3 on Ubuntu

1. How to install sqlite3 on ubuntu?

$apt-get install sqlite3 libsqlite3-dev or

$sudo apt-get install sqlite3 libsqlite3-devif you are not admin/root

2. How to create a new database?

$sqlite3 dbname.db

This will take you to sqlite3 interactive shell sqlite>

• sqlite>.help for help
• sqlite3>.quit to exit
• sqlite>.read myscript.sql to run a SQL script
• sqlite>select * from cities; to run a query

3. How to connect to an existing DB?

$sqlite3 dbname.db

or

$sqlite3 then sqlite>.open dbname.db

Installation

1. on Windows, open git bash shell
2. $ssh das10
3. $cd pythonwork
4. $git clone https://github.com/wcj365/flask-sql.git
5. $cd flask-sql
6. $python3 -m venv venv
7. $source venv/bin/activate
8. (venv)$pip install -r requirements.txt