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FastAPI 0.155.0 removes the deprecated **extra escape hatch
By RepoJournal · Filed · About FastAPI & Pydantic · Composed from the cited sources · methodology
FastAPI 0.155.0 drops the deprecated **extra keyword arguments from every request parameter class, so unknown keywords that used to be silently swallowed into the JSON Schema now raise TypeError, and the release notes give the migration: replace Query(custom="value") with Query(json_schema_extra={"custom": "value"}).
0.155.0 fastapi/fastapi
The deprecated **extra keyword arguments are gone from Path, Query, Header, Cookie, Body, Form, and File; unknown keywords now raise TypeError instead of being folded into the schema. Any parameter declaration relying on the old shorthand has to move to json_schema_extra.
✨ Add Pydantic validation options to request parameters fastapi/fastapi
Request parameters gain Pydantic validation options, extending the validation surface that previously lived mostly on models down to individual Path, Query, and body declarations.
🐛 Distinguish JSON null from omitted body values fastapi/fastapi
JSON null in a body field is now distinguished from a field that was omitted entirely, so optional body values no longer collapse into the same case at validation time.
🔥 Remove deprecated `**extra` from request parameters fastapi/fastapi
The **extra removal is the single breaking change in this release, landing under tiangolo and flagged in the PR as written with Codex under manual review.
Support named tuples in `Sequence` serialization pydantic/pydantic
On the Pydantic side, the long tail was maintenance: named tuples now serialize correctly inside Sequence, following the earlier sequence work, plus a deferral of date.today() evaluation in date validation tests so parametrized dates no longer freeze at pytest collection time and fail across UTC midnight in CI.
Action items
- → Audit FastAPI parameter declarations for **extra keywords and replace Query(custom="value") with Query(json_schema_ex... fastapi/fastapi [immediate]
