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fastapi_5077

resolved RESOLVED UNSUBMITTED PASS · None tool calls · 0 s · fastapi/fastapi

Task input

✨ Add support for wrapped functions (e.g. `@functools.wraps()`) used with forward references

Fixes #5065 where the `globalns` computation in `get_typed_signature` misses an edge case handled by `typing.get_type_hints`. This PR makes the logic similar to `get_type_hints`.

## Background

`functools.wraps` updates the annotations and type signature to match the wrapped function. However, it copies the `__annotations__` dict verbatim, including forward references (strings). `get_type_hints` handles this by [dereferencing the `__wrapped__` attribute](https://github.com/python/cpython/blob/576dd901170af30fc50b0a7f07a388b38fd724a9/Lib/typing.py#L2314-L2315) until it gets to the original function, then uses the `__globals__` of _that_ function.

## Testing

I added a test case which reproduced the `NameError` seen in #5065. The test passes after my commit updating the implementation of `get_typed_signature`:

```
tests/test_wrapped_method_forward_reference.py:24:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
fastapi/routing.py:617: in decorator
    self.add_api_route(
fastapi/routing.py:556: in add_api_route
    route = route_class(
fastapi/routing.py:425: in __init__
    self.dependant = get_dependant(path=self.path_format, call=self.endpoint)
fastapi/dependencies/utils.py:279: in get_dependant
    endpoint_signature = get_typed_signature(call)
fastapi/dependencies/utils.py:249: in get_typed_signature
    typed_params = [
fastapi/dependencies/utils.py:254: in <listcomp>
    annotation=get_typed_annotation(param, globalns),
fastapi/dependencies/utils.py:266: in get_typed_annotation
    annotation = evaluate_forwardref(annotation, globalns, globalns)
pydantic/typing.py:76: in pydantic.typing.evaluate_forwardref
    ???
../../.pyenv/versions/3.9.1/lib/python3.9/typing.py:533: in _evaluate
    eval(self.__forward_code__, globalns, localns),
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

>   ???
E   NameError: name 'ForwardRef' is not defined

<string>:1: NameError
============================================================== short test summary info ===============================================================
FAILED tests/test_wrapped_method_forward_reference.py::test_wrapped_method_type_inference - NameError: name 'ForwardRef' is not defined
================================================================= 1 failed in 0.59s ==================================================================
```

Tool calls (0)

Patch

--- a/fastapi/dependencies/utils.py
+++ b/fastapi/dependencies/utils.py
@@ -192,7 +192,8 @@ def get_flat_params(dependant: Dependant) -> List[ModelField]:
 
 def get_typed_signature(call: Callable[..., Any]) -> inspect.Signature:
     signature = inspect.signature(call)
-    globalns = getattr(call, "__globals__", {})
+    unwrapped = inspect.unwrap(call)
+    globalns = getattr(unwrapped, "__globals__", {})
     typed_params = [
         inspect.Parameter(
             name=param.name,
@@ -217,12 +218,13 @@ def get_typed_annotation(annotation: Any, globalns: Dict[str, Any]) -> Any:
 
 def get_typed_return_annotation(call: Callable[..., Any]) -> Any:
     signature = inspect.signature(call)
+    unwrapped = inspect.unwrap(call)
     annotation = signature.return_annotation
 
     if annotation is inspect.Signature.empty:
         return None
 
-    globalns = getattr(call, "__globals__", {})
+    globalns = getattr(unwrapped, "__globals__", {})
     return get_typed_annotation(annotation, globalns)
 
 

Test output

.                                                                        [100%]
=============================== warnings summary ===============================
../../../../../../../Users/jp/repos/kaggle-gemini-coding-agent-post-training/.envs/overlays/starlette-0.50.0-py3-none-any/starlette/testclient.py:45
  /Users/jp/repos/kaggle-gemini-coding-agent-post-training/.envs/overlays/starlette-0.50.0-py3-none-any/starlette/testclient.py:45: DeprecationWarning: The anyio.abc.BlockingPortal alias is deprecated, use anyio.from_thread.BlockingPortal instead.
    _PortalFactoryType = Callable[[], AbstractContextManager[anyio.abc.BlockingPortal]]

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html
1 passed, 1 warning in 0.66s