A rename did not actually take effect. @JsonProperty stopped the old name
from being *mapped*, but not from being *accepted*: unlike @JsonReadOnly,
whose JSON name goes into the blocked set, the old key fell through to the
unknown-key policy, and the default `allow` copied it onto the instance
untouched.
The value therefore landed on a declared property having skipped everything
declared for it:
@JsonProperty('home_address') @JsonType(() => Addr) @ValidateNested()
address!: Addr;
toInstanceSync(Order, { address: { city: 'Paris' } })
-> address is a plain object, instanceof Addr === false
-> validateSync() returns [] <- nothing complains
A payload aimed at the previous version of a class was accepted in part, in
silence. Three routes led to the same hole, and all three are now closed:
- the property key of a field renamed with @JsonProperty
- the raw key of a field a naming strategy renders differently
(`firstName` under snake_case)
- the property key of a field that is both renamed and @JsonReadOnly, which
was still settable under its own key
Refused, not swallowed. A stale name is a mismatch with whatever produced
the payload, not a deliberate refusal like @JsonReadOnly, so it is kept in
its own map rather than lumped into `blocked`: under unknownKeys: 'error'
it is still reported, and the report now names the property it was reaching
for and what that property is called now.
"ref" is not a JSON name for Order: property "ref" is mapped to
"order_ref". Send that name, or add @JsonAlias("ref") to keep
accepting this one.
@JsonAlias still keeps an old name working, and a key that some *other*
property legitimately answers to is still mapped to that property — both
asserted. The resolution happens once when the name map is built, which is
memoized per class and naming strategy, so deserialization is unchanged at
~45µs for 50 nested orders.
The behaviour this replaces was pinned by tests two commits ago, pending
this decision; those tests now assert the fix, and six more cover the
naming-strategy, read-only, alias and key-collision cases.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SAcqrz3FcadkYr3xG32CjK
Claude
478f852b42