A library whose headline feature is "JSON mapping" could not map a name: there
was no way to read {"first_name": ...} into firstName, no way to keep a password
out of the response, and no way to parse a payload without validating it.
Name mapping
- @JsonProperty(name) renames a property in both directions
- @JsonAlias(...names) accepts extra names on input only, so a field can be
renamed without breaking older clients
- naming strategies (snake_case, kebab-case, SCREAMING_SNAKE_CASE, PascalCase,
camelCase, or your own function) for properties with no explicit name.
Acronyms split where a reader expects: parseHTTPResponse -> parse_http_response
Access control
- @JsonIgnore() excluded both ways
- @JsonWriteOnly() accepted from input, never echoed back (passwords)
- @JsonReadOnly() serialized, never settable by a client (server-owned ids)
Blocked names are dropped explicitly rather than falling through to the unknown
key path, which would otherwise have copied a rejected id straight back on under
the default policy.
Transform options, per call or globally via configure()
- validate: false to map without validating, for lenient parsing
- unknownKeys: 'allow' | 'strip' | 'error'
- namingStrategy
Error ergonomics — the nested ValidationError tree was hard to turn into an HTTP
400 body. flattenErrors() yields {"items[0].qty": ["qty must be at least 1"]},
plus formatErrors() and collectErrorMessages(). Adds validateOrReject().
All defaults preserve existing behaviour; the 68 prior tests pass unchanged.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SAcqrz3FcadkYr3xG32CjK
