JSTEP 2

(Back to JSTEP page)

---

Jackson 3 default settings, behavior changes

Author

Tatu Saloranta (@cowtowncoder)

Version history

• 2024-05-31: MapperFeature.ALLOW_FINAL_FIELDS_AS_MUTATORS default changed
• 2024-03-01: minor update on default changes
• 2022-09-18: add proposed default change to Date/Times-as-timestamps DeserializationFeatures
• 2019-02-10: create first version from earlier notes

Overview

During Jackson 2.x development, certain default settings have proven either problematic by development team, or non-intuitive/non-optimal by users: latter indicated both by filed issues and comments on mailing list discussions. Since default settings and behavior are important part of the public API, changes have had to wait until major version change in most cases.

This document details proposed/planned changes.

Prior Work

Note that at the time of writing (February 2019), some of the work has already been done. Attempt is made to include such changes in this plan as if work was being planned, even if initial changes have been made.

Changes to jackson-core defaults

JsonReadFeature

No changes

JsonWriteFeature

• JsonWriteFeature.ESCAPE_FORWARD_SLASHES now defaults to true

StreamReadConstraints

• DEFAULT_MAX_DEPTH to 500 (from 1,000) (see core#1233)

StreamWriteConstraints

• DEFAULT_MAX_DEPTH to 500 (from 1,000) (see core#1233)

StreamReadFeature

• USE_FAST_DOUBLE_PARSER: enabled by default in 3.0 (see core#1231)
• USE_FAST_BIG_NUMBER_PARSER: enabled by default in 3.0 (see core#1231)

StreamWriteFeature

• USE_FAST_DOUBLE_WRITER: enabled by default in 3.0 (see core#1231)

Changes to jackson-databind defaults

MapperFeature

First, following deprecated features are to be removed from 3.0:

• USE_STD_BEAN_NAMING: should always be enabled, no need for old slightly differing algorithm
• AUTO_DETECT_xxx: old limited settings superceded by more granular settings -- frees up 5 features

And defaults to following features have been changed:

• ALLOW_FINAL_FIELDS_AS_MUTATORS: default to false -- while enabling may be useful sometimes, it confuses users in general and is unlikely to even work with future JDKs/JVMs
  • databind#4552
• USE_GETTERS_AS_SETTERS: default to false -- earlier default was based on JAXB but is quite confusing for users
  • databind#1916

And defaults to following features are considered for change:

• SORT_PROPERTIES_ALPHABETICALLY: default to true (false really doesn't make much sense since it is unstable, and arbitrary based on JVM/JDK)

DeserializationFeature

Changes to defaults:

• READ_ENUMS_USING_TO_STRING: default to true (instead of false that relies on name())
• FAIL_ON_UNKNOWN_PROPERTIES: default to false? (TOP REQUEST by users)
• FAIL_ON_UNEXPECTED_VIEW_PROPERTIES: default to true (as per databind#437)

Other changes, potential:

• Although all features still make sense, would make sense to try to combine some, and/or create new type of configuration to use instead of feature -- for example
  • FAIL_xxx are all kind of similar. DeserializationFail, or "check" or... ?
  • READ_xxx_as_yyy, similarly
  • ACCEPT_xxx_as_yyy, similarly

SerializationFeature

Changes to defaults:

• FAIL_ON_EMPTY_BEANS: default to false
• Writing date/time values as ISO-8601 Strings instead of (Java style) timestamps
  • WRITE_DATES_AS_TIMESTAMPS: change default to false to serialize as ISO-8601 String
  • WRITE_DATE_KEYS_AS_TIMESTAMPS: RETAIN default of false -- no change
  • WRITE_DURATIONS_AS_TIMESTAMPS: change default to false to serialize as ISO-8601 String

Other changes, potential:

• Most if not all features seem to make sense, but there are groups that could use unification of some kind
  • FAIL_ON_xxx
  • WRITE_xxx_as_yyy

Changes to Date/Time defaults

• Disable lenient setting (that is: default to "strict")
• Check defaults of date/time handling

Misc other default setting, behavior changes

JsonNode handling

• DecimalNode creation via JsonNodeFactory: default to NOT truncating trailing zeroes (minimal trimming), because JsonNode should by default expose content as close to way it came.