Raise clear NameError at route registration for unresolvable forward-reference annotations#15307
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Dima-Bulavenko wants to merge 4 commits intofastapi:masterfrom
Open
Raise clear NameError at route registration for unresolvable forward-reference annotations#15307Dima-Bulavenko wants to merge 4 commits intofastapi:masterfrom
Dima-Bulavenko wants to merge 4 commits intofastapi:masterfrom
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The test implies that the code that causes coverage issue won't be run
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This PR is related to #13056
Problem
When
from __future__ import annotationsis used and a type isn't available at route registration time (e.g. defined after the route, or imported only underTYPE_CHECKING), FastAPI silently swallows the unresolved forward reference. This leads to wrong behavior when unresolved annotation of a parameter quietly becomes a query parameter . The actual error only shows up later as a Pydantic error failure when the route is called or docs are generated.I looked into fully fixing #13056 and IMO the only solutions to fix it is by deferring annotation resolution to request time, but that would mean rewriting large parts of route initializator for such minor issue.
Solution
Instead of silently producing wrong behavior, fail immediately at route registration with a clear error message that tells the developer what went wrong and how to fix it.
What changed
eval_type_lenienttotry_eval_typeget_typed_annotationfunction isForwardRefannotation wasn't resolvedget_typed_annotationand for routes with valida and invalid types