Change of behavior (2.8 -> 2.9) with `ObjectMapper.readTree(input)` with no content #2211

cowtowncoder · 2018-12-18T20:45:27Z

So, it looks like readTree() methods in ObjectMapper, ObjectReader that take input OTHER than JsonParser, and are given "empty input" (only white-space available before end), will

Return NullNode (Jackson 2.x up to and including 2.8)
Return null (Jackson 2.9)

Latter behavior is what readTree(JsonParser) has and will do; but this accidentally changed other methods due to refactoring that unified underlying call handling (and add checking for new DeserializationFeature.FAIL_ON_TRAILING_TOKENS).
Behavior for this edge case was not being tested, apparently.

Now: since behavior has been changed for all 2.9.x patch versions, I am not sure it should be changed for 2.9 branch. But it seems sub-optimal as behavior, and something to definitely change for 3.0... but probably also for 2.10.

There are multiple things we could do.

Change it back to 2.8, to return NullNode
Change to throw exception, as "not valid" use case
Change it to return MissingNode
Leave as-is, for rest of 2.x.

Although it might seem best to revert it to (1), that seems somewhat wrong, problematic, as it would now not be possible to distinguish between JSON null value and missing content.
And although (2) would probably make sense, if designing API from scratch, it is probably too intrusive.

So I think (3) is the best way: it avoids returning null or throwing Exception (both being likely to break 2.9 code), but still allows distinguishing between all possible input cases.

The text was updated successfully, but these errors were encountered:

cowtowncoder · 2019-01-23T05:37:58Z

Note: once upon a time there was #1406, which actually makes this intentional but misguided change.

…values FasterXML/jackson-databind#2211 - In Jackson <2.9.0 an IOException was raised - In Jackson >=2.9.0, null is returned

* Allow trailing comma in Gelf JSON parser * Update jackson to 2.9.9 * Keep exsiting behavior when using objectMapper.readTree() with empty values FasterXML/jackson-databind#2211 - In Jackson <2.9.0 an IOException was raised - In Jackson >=2.9.0, null is returned

…response with no content. Jackson 2.10 changed the behavior for ObjectMapper.readTree(input) for no content (see: FasterXML/jackson-databind#2211).

…NG JsonNodeType in JsonConverter. From 2.10.0 onwards, in jackson lib, ObjectMapper.readTree(input) started to return JsonNode of type MISSING for empty input, as mentioned in the issue: FasterXML/jackson-databind#2211. Made changes in JsonParser to incorporate this, and treat MISSING JsonNodeType in a similar fashion as that of NULL JsonNodeType. Added a unit test for this.

…ULL nodes (#9306) Fixes a regression introduced in `JsonConverter` with previous upgrades from Jackson Databind 2.9.x to 2.10.x. Jackson Databind version 2.10.0 included a backward-incompatible behavioral change to use `JsonNodeType.MISSING` (and `MissingNode`, the subclass of `JsonNode` that has a type of `MISSING`) instead of `JsonNodeType.NULL` / `NullNode`. See FasterXML/jackson-databind#2211 for details of this change. This change makes recovers the older `JsonConverter` behavior of returning null on empty input. Added two unit tests for this change. Both unit tests were independently tested with earlier released versions and passed on all versions that used Jackson 2.9.x and earlier, and failed on all versions that used 2.10.x and that did not have the fixed included in the PR. Both of the new unit tests pass with this fix to `JsonConverter`. Author: Shaik Zakir Hussain <zhussain@confluent.io> Reviewer: Randall Hauch <rhauch@gmail.com>

Two of the tests were waiting for log output using a one-off call to Thread.sleep(). In addition to being brittle, the tests would fail with an NPE (while trying to assert on the "timestamp" field) that doesn't point to the cause of the failure directly. Also removed the redundant assertThat(jsonNode).isNotNull() as objectMapper.readTree() will never return null in Jackson 2.10.x, see FasterXML/jackson-databind#2211

Two of the tests were waiting for log output using a one-off call to `Thread.sleep()`. In addition to being brittle, the tests would fail with an NPE (while trying to assert on the "timestamp" field) that doesn't point to the cause of the failure directly. Also removed the redundant null-check as `objectMapper.readTree()` will never return `null` in Jackson 2.10.x, see FasterXML/jackson-databind#2211

Two of the tests were waiting for log output using a one-off call to `Thread.sleep()`. In addition to being brittle, the tests would fail with an NPE (while trying to assert on the "timestamp" field) that doesn't point to the cause of the failure directly. Also removed the redundant null-check as `objectMapper.readTree()` will never return `null` in Jackson 2.10.x, see FasterXML/jackson-databind#2211 (cherry picked from commit bdb829c)

cowtowncoder added ACTIVE labels Dec 18, 2018

cowtowncoder changed the title ~~Change of behavior (2.8 -> 2.9) with ObjectMappe.readTree(input) with no content~~ Change of behavior (2.8 -> 2.9) with ObjectMapper.readTree(input) with no content Dec 20, 2018

cowtowncoder added a commit that referenced this issue Jan 20, 2019

Working on tests for #2211

aea65f1

cowtowncoder mentioned this issue Jan 23, 2019

ObjectMapper.readTree() methods do not return null on end-of-input #1406

Closed

cowtowncoder added a commit that referenced this issue Jan 23, 2019

More work on #2211

f0abe41

cowtowncoder added a commit that referenced this issue Jan 23, 2019

Javadoc improvements wrt #2211

21220ee

cowtowncoder closed this as completed in e797b22 Jan 24, 2019

cowtowncoder removed the ACTIVE label Jan 24, 2019

cowtowncoder added this to the 2.10.0 milestone Jan 24, 2019

PascalSchumacher mentioned this issue Sep 20, 2019

Update Jackson to version 2.10.1 flowable/flowable-engine#1947

Closed

cowtowncoder removed the 2.10 label Apr 12, 2020

shaikzakiriitm mentioned this issue Sep 18, 2020

KAFKA-10477: Enabling the same behavior of NULL JsonNodeType to MISSI… apache/kafka#9306

Merged

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thll mentioned this issue Oct 5, 2022

Update to jackson 2.13 Graylog2/graylog2-server#13541

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Change of behavior (2.8 -> 2.9) with `ObjectMapper.readTree(input)` with no content #2211

Change of behavior (2.8 -> 2.9) with `ObjectMapper.readTree(input)` with no content #2211

cowtowncoder commented Dec 18, 2018 •

edited

cowtowncoder commented Jan 23, 2019 •

edited

Change of behavior (2.8 -> 2.9) with ObjectMapper.readTree(input) with no content #2211

Change of behavior (2.8 -> 2.9) with ObjectMapper.readTree(input) with no content #2211

Comments

cowtowncoder commented Dec 18, 2018 • edited

cowtowncoder commented Jan 23, 2019 • edited

Change of behavior (2.8 -> 2.9) with `ObjectMapper.readTree(input)` with no content #2211

Change of behavior (2.8 -> 2.9) with `ObjectMapper.readTree(input)` with no content #2211

cowtowncoder commented Dec 18, 2018 •

edited

cowtowncoder commented Jan 23, 2019 •

edited