← pod_r2_v1f

fastapi_14306

failed WRONG_FIX UNSUBMITTED wrong_fix_unsubmitted(timeout) · 55 tool calls · 0 s · fastapi/fastapi

Task input

🚸  Improve tracebacks by adding endpoint metadata

Today, when validation errors occur, error messages don't indicate what endpoint caused the problem, which can make debugging difficult. 

This PR adds endpoint context metadata to validation error messages to show the filepath (clickable in IDEs!) and line number, function name and HTTP method and route where applicable. The endpoint context is extracted once per endpoint and then cached to avoid any additional performance overhead on subsequent requests. Just to double check, I also ran a rough benchmark (100k requests):
```
Baseline (without changes):     0.0006s
Uncached:     					1.3281s (13.28µs per request)
**Cached**:       				0.0060s (0.06µs per request)
```

Endpoint context only appears in the exception's string representation (server logs). It is **not** exposed to clients in HTTP responses. Clients still receive the standard 422 response with validation error details.

## Examples

### ResponseValidationError

**Before:**
```
fastapi.exceptions.ResponseValidationError: 1 validation error:
  {'type': 'missing', 'loc': ('response', 'id'), 'msg': 'Field required', 'input': {'name': 'Widget'}}
```

**After:**
```
fastapi.exceptions.ResponseValidationError: 1 validation error:
  {'type': 'missing', 'loc': ('response', 'id'), 'msg': 'Field required', 'input': {'name': 'Widget'}}

  File "/Users/savannah/work/fastapi/capture_real_examples.py", line 43, in create_item
    POST /items/
```

### RequestValidationError

**Before:**
```
fastapi.exceptions.RequestValidationError: 1 validation error:
  {'type': 'int_parsing', 'loc': ('path', 'user_id'), 'msg': 'Input should be a valid integer, unable to parse string as an integer', 'input': 'invalid'}
```

**After:**
```
fastapi.exceptions.RequestValidationError: 1 validation error:
  {'type': 'int_parsing', 'loc': ('path', 'user_id'), 'msg': 'Input should be a valid integer, unable to parse string as an integer', 'input': 'invalid'}

  File "/Users/savannah/work/fastapi/capture_real_examples.py", line 38, in get_user
    GET /users/{user_id}
```

### WebSocketRequestValidationError

**Before:**
```
fastapi.exceptions.WebSocketRequestValidationError: 1 validation error:
  {'type': 'int_parsing', 'loc': ('path', 'item_id'), 'msg': 'Input should be a valid integer, unable to parse string as an integer', 'input': 'invalid'}
```

**After:**
```
fastapi.exceptions.WebSocketRequestValidationError: 1 validation error:
  {'type': 'int_parsing', 'loc': ('path', 'item_id'), 'msg': 'Input should be a valid integer, unable to parse string as an integer', 'input': 'invalid'}

  File "/Users/savannah/work/fastapi/capture_real_examples.py", line 48, in websocket_endpoint
    WS /ws/{item_id}
```

Tool calls (0)

Patch

diff --git a/fastapi/exceptions.py b/fastapi/exceptions.py
index 0620428b..0bda1d65 100644
--- a/fastapi/exceptions.py
+++ b/fastapi/exceptions.py
@@ -157,10 +157,19 @@ class DependencyScopeError(FastAPIError):
 class ValidationException(Exception):
     def __init__(self, errors: Sequence[Any]) -> None:
         self._errors = errors
+        self.endpoint_context: Optional[str] = None
 
     def errors(self) -> Sequence[Any]:
         return self._errors
 
+    def __str__(self) -> str:
+        message = f"{len(self._errors)} validation errors:\n"
+        for err in self._errors:
+            message += f"  {err}\n"
+        if self.endpoint_context:
+            message += f"\n{self.endpoint_context}"
+        return message
+
 
 class RequestValidationError(ValidationException):
     def __init__(self, errors: Sequence[Any], *, body: Any = None) -> None:

Test output

F
=================================== FAILURES ===================================
___________ test_request_validation_error_includes_endpoint_context ____________

    def test_request_validation_error_includes_endpoint_context():
        captured_exception.exception = None
        try:
            client.get("/users/invalid")
        except Exception:
            pass
    
        assert captured_exception.exception is not None
        error_str = str(captured_exception.exception)
>       assert "get_user" in error_str
E       assert 'get_user' in "1 validation errors:\n  {'type': 'int_parsing', 'loc': ('path', 'user_id'), 'msg': 'Input should be a valid integer, unable to parse string as an integer', 'input': 'invalid'}\n"

tests/test_validation_error_context.py:96: AssertionError
=============================== 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
!!!!!!!!!!!!!!!!!!!!!!!!!! stopping after 1 failures !!!!!!!!!!!!!!!!!!!!!!!!!!!
1 failed, 1 warning in 0.49s