Fix `@JsonAnyGetter` keys not prefixed when inner bean uses `@JsonUnwrapped(prefix=...)` by pjfanning · Pull Request #6123 · FasterXML/jackson-databind

pjfanning · 2026-07-25T20:29:26Z

When @JsonAnyGetter appears on a bean referenced via @JsonUnwrapped(prefix="..."), the prefix was never applied to the any-getter map keys. Worse, AnyGetterWriter didn't override rename(NameTransformer), so the inherited path called _new(PropertyName) which throws IllegalStateException for subclasses — crashing serializer construction.

Example

class Outer {
    public String name = "aaa";
    @JsonUnwrapped(prefix = "a-")
    public Inner inner; // inner.getExtra() returns {"age": "64"}
}
// Before fix: IllegalStateException at mapper construction, or wrong output
// After fix:  {"name":"aaa","a-age":"64"}

Changes

`AnyGetterWriter`

Added NameTransformer _nameTransformer field (null in normal, non-unwrapped use)
Added protected copy constructor AnyGetterWriter(AnyGetterWriter src, NameTransformer transformer) with correct chaining: chainedTransformer(newTransformer, src._nameTransformer), matching the ordering in UnwrappingBeanPropertyWriter
Overrode rename(NameTransformer) to return a copy storing the transformer rather than attempting to rename the property itself (meaningless for any-getter)
getAndSerialize() and getAndFilter() now dispatch to transformer-aware helpers when _nameTransformer != null, applying it to each map/ObjectNode key individually

`UnwrappedWithAnySetterTest`

Added testUnwrappedWithPrefixWithAnyGetter covering the bug scenario: outer direct field serializes without prefix; inner any-getter entries get the "a-" prefix applied per key

pjfanning · 2026-07-26T11:14:28Z

There is still an issue with deserialization of maps when unwrapped with prefix is used. The deserialization of the map doesn't remove the prefix. I want to treat that as a separate issue and can work out a fix for that if and when this serialization fix is merged.

github-actions · 2026-07-26T20:07:50Z

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pjfanning · 2026-07-26T20:07:58Z

@cowtowncoder I fixed the deserialization issue with AI assistance. The issue I described above (#6123 (comment))

pjfanning · 2026-07-26T20:15:48Z

+     * can be reverse-transformed before being passed to
+     * {@code @JsonAnySetter}.
+     *
+     * @since 3.3


I have put version 3.3 on all the since markers but can change them to 3.1 or 3.2 if this is deemed safe for backporting

github-actions · 2026-07-26T20:19:04Z

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github-actions · 2026-07-29T22:22:53Z

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cowtowncoder · 2026-07-29T22:39:08Z

Ok. AI review pointed out a seemingly serious issue:

Correctness issue — confirmed regression (high severity)

AnyGetterWriter._serializeMapEntriesWithTransformer() (the new fallback used whenever _nameTransformer != null) completely bypasses _mapSerializer for real java.util.Map values, replacing it with a hand-rolled loop: rawKey.toString() for keys and ctxt.writeValue(gen, entryValue) for values. This silently drops everything MapSerializer normally provides:

Content inclusion filtering (@JsonInclude(NON_NULL)/NON_EMPTY etc. on the any-getter map) — I reproduced this concretely: with @JsonInclude(NON_NULL) on the extra map, a null-valued entry that's correctly suppressed when the bean is not unwrapped is emitted ("a-nickname":null) once the same bean is referenced via @JsonUnwrapped(prefix="a-").
Custom key serializers (_keySerializer, e.g. @JsonSerialize(keyUsing=...), non-String keys with custom formatting) — silently downgraded to Object.toString().
Whatever else MapSerializer.serializeFilteredAnyProperties()/serializeWithoutTypeInfo() do beyond the naive loop (polymorphic value typing, etc.).

This means: for any bean that combines @JsonAnyGetter + @JsonUnwrapped(prefix/suffix=...), Map serialization semantics silently regress the moment a name-transform is in play — trading one bug (missing prefix) for a different, arguably worse one (silently wrong output for filtered/keyed maps). A better approach would push the key transformation into the existing MapSerializer path (e.g., wrap/rename the key after _keySerializer runs, or pass the transformer into serializeWithoutTypeInfo/serializeFilteredAnyProperties) rather than routing around it.

I'll see if that can be fixed; that cannot be merged as-is.

pjfanning · 2026-07-29T23:22:50Z

@cowtowncoder I got AI to sort some of the issues but there might be more.

github-actions · 2026-07-29T23:23:03Z

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cowtowncoder · 2026-07-30T03:47:38Z

@pjfanning Hoping to pick this up soon, maybe tomorrow.

github-actions · 2026-08-12T02:33:18Z

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github-actions · 2026-08-12T03:59:26Z

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…refix), add test

…sformer

…wrapped 'inner'

github-actions · 2026-08-21T19:47:06Z

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pjfanning · 2026-08-21T19:47:22Z

I got Claude Opus to write extra tests and it has 7 that fail and they are annotated so they don't run.

Test coverage for `@JsonUnwrapped(prefix)` + `@JsonAnyGetter`/`@JsonAnySetter`

Added 24 tests across two files. All pass; the 7 in tofix/ pass because they fail — each is a real
edge case where the PR (#6123) breaks down.

What works — `struct/UnwrappedWithAnyGetterPrefixTest.java` (17 tests)

prefix / suffix / prefix+suffix round-trips
plain @JsonUnwrapped (NOP transformer) unchanged
keys that already contain the prefix (a-age → a-a-age → a-age)
empty any-getter map writes nothing
any-getter/any-setter declared on a field
ObjectNode-valued any-getter ([databind#3604]) — nested node keys correctly left alone
enum map keys
custom (non-MapSerializer) any-getter serializer via @JsonSerialize(using=...)
property-based creator on the unwrapped bean
@JsonIdentityInfo outer, polymorphic (@JsonTypeInfo) outer
nested @JsonUnwrapped prefixes chaining on write (a-b-age)
two prefixed unwrapped beans on write
handler-cache safety: same inner type used with different prefixes and standalone

What doesn't — `tofix/UnwrappedAnyGetterPrefixTest.java` (7 tests)

#	Failure	Cause
1	`{"a-obj":{"a-x":1,"a-y":2}}` — nested Map/Array keys prefixed	`NameTransformingGenerator` intercepts every `writeName`, at any depth, not just the any-getter's own keys
2	`{"a-pt":{"a-x":1,"a-y":2}}` — nested POJO properties prefixed	same
3	`{"a-pet":{"a-@type":"dog",…}}` — polymorphic type id prefixed	same
4	`{"3":"x"}` — `Integer`/`Long` keys get no prefix	those go through `JsonGenerator.writePropertyId(long)`, which the delegate doesn't override (String/enum/`byte[]` keys use `writeName` and do work)
5	Builder-based inner: any-setter receives `a-age`	`BuilderBasedDeserializer.unwrappingDeserializer()` doesn't retain the `NameTransformer` the way `BeanDeserializer` now does
6	Two prefixed unwrapped beans: each any-setter collects the other's props (`a.ea = {p=1, b-q=2}`)	when `reverse()` returns `null` the raw name is passed through instead of being skipped — writes are correct, so the value doesn't round-trip
7	Nested `@JsonUnwrapped` prefixes: `a-b-age` silently dropped on read	pre-existing, but write now emits `a-b-age`, so the new serialization side has no working read side

Provenance: items 1–4 are new with this branch — on the base commit (30e603d3f) this whole scenario
threw IllegalStateException: Method must be overridden by class AnyGetterWriter. Items 5 and 6 are
unchanged-but-wrong. Item 7 predates the branch (verified in a worktree at 30e603d3f).
Items 1–3 were checked against a non-unwrapped baseline, which correctly produces {"obj":{"x":1}}.

Suggested fixes

1–3 (the serious one) — a generator wrapper can't tell depth apart. Either make
NameTransformingGenerator transform only at the depth it was installed (track
writeStartObject/writeEndObject nesting, transform only when depth == 0), or drop the wrapper
and transform keys explicitly in a MapSerializer entry loop.
4 — override writePropertyId(long) in NameTransformingGenerator:
delegate.writeName(_transformer.transform(String.valueOf(id))).
5 — mirror the BeanDeserializer change in BuilderBasedDeserializer.
6 — skip the property (rather than passing the raw name) when reverse() returns null.
Safe, since the no-prefix case uses NameTransformer.NOP, whose reverse() never returns null.

github-actions · 2026-08-21T19:57:39Z

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github-actions · 2026-08-21T20:06:46Z

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github-actions · 2026-08-21T20:17:40Z

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github-actions · 2026-08-21T20:40:27Z

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gitar-bot · 2026-08-21T21:12:05Z

Code Review ✅ Approved 2 resolved / 2 findings

Fixes @JsonAnyGetter map key prefixing under @JsonUnwrapped(prefix=...) by updating AnyGetterWriter to support NameTransformer, addressing the name transforming and double reverse computation findings. No issues found.

✅ 2 resolved

✅ Bug: NameTransformingGenerator prefixes nested object keys too

✅ Performance: reverse() computed twice per accepted any-setter property

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github-actions · 2026-08-21T21:14:23Z

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pjfanning changed the title ~~possible fix for 6118~~ Fix @JsonAnyGetter keys not prefixed when inner bean uses @JsonUnwrapped(prefix=...) Jul 25, 2026

pjfanning mentioned this pull request Jul 26, 2026

add test to UnwrappedWithAnySetterTest to highlight issue raised in 6118 #6122

Closed

pjfanning commented Jul 26, 2026

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gitar-bot Bot reviewed Aug 12, 2026

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Comment thread src/main/java/tools/jackson/databind/ser/NameTransformingGenerator.java

Copilot AI and others added 9 commits August 21, 2026 20:14

Fix @JsonAnyGetter prefix not applied when used with @JsonUnwrapped(p…

701545b

…refix), add test

Address review: fix null key handling in _serializeMapEntriesWithTran…

f1a7e6c

…sformer

Update UnwrappedWithAnySetterTest.java

4e5b333

Fix property ordering: add @JsonPropertyOrder to put 'name' before un…

f48c460

…wrapped 'inner'

Update AnyGetterWriter.java

a296ce1

try to fix read side of JsonUnwrapped(prefix=....) for maps

f5b30b4

Update BeanDeserializer.java

a5f2acc

try to fix of the issues

371787d

more tests

06834b4

pjfanning force-pushed the copilot/unwrapped-test branch from 3381453 to 06834b4 Compare August 21, 2026 19:43

fix 3 tests

9e1ab48

fix more tests

5a6f1b4

another issue fixed

1ccbe62

gitar-bot Bot reviewed Aug 21, 2026

View reviewed changes

Comment thread src/main/java/tools/jackson/databind/deser/bean/BeanDeserializerBase.java Outdated

fix another tofix test

7150a33

pjfanning added 2 commits August 21, 2026 21:55

address review issue about double reverse

697f98a

last broken test

5550dfb

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Correctness issue — confirmed regression (high severity)

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pjfanning commented Aug 21, 2026

Test coverage for @JsonUnwrapped(prefix) + @JsonAnyGetter/@JsonAnySetter

What works — struct/UnwrappedWithAnyGetterPrefixTest.java (17 tests)

What doesn't — tofix/UnwrappedAnyGetterPrefixTest.java (7 tests)

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pjfanning commented Jul 25, 2026 •

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Test coverage for `@JsonUnwrapped(prefix)` + `@JsonAnyGetter`/`@JsonAnySetter`

What works — `struct/UnwrappedWithAnyGetterPrefixTest.java` (17 tests)

What doesn't — `tofix/UnwrappedAnyGetterPrefixTest.java` (7 tests)