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fastapi_14479

failed NO_PATCH NO_PATCH UNSUBMITTED empty_patch(None) · None tool calls · 0 s · fastapi/fastapi

Task input

🚸 Improve error message for invalid query parameter type annotations

When I bumped FastAPI from 0.181.1 to 0.181.2, project started crashing on startup with AssertionError. The traceback didn’t provide any helpful context. After debugging, I found that issue was caused by incorrectly typed query parameters after the changes introduced in PR #12942 

This PR adds a clearer error message to assertion, indicating that query parameter type is incorrect, and updates tests to ensure that new message is present.

Below is an example of a wrongly typed query parameter that didn’t fail before 0.181.2, but starts failing in 0.181.2 and later:
```python
from typing import Annotated, Any
from fastapi import FastAPI, Query
from pydantic import BeforeValidator, WithJsonSchema

app = FastAPI()

FilterableStr = Annotated[
    str | dict,
    BeforeValidator(lambda x: x),
    WithJsonSchema({"type": "string"}, mode="serialization"),
]

@app.get("/hello")
async def get_hello(data: FilterableStr | None = Query(default=None)) -> Any:
    return data
```


Stacktrace before:
```python
  File "/Users/tony/Projects/fastapi_exampl/.venv/lib/python3.13/site-packages/fastapi/routing.py", line 630, in __init__
    self.dependant = get_dependant(path=self.path_format, call=self.endpoint)
                     ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/tony/Projects/fastapi_exampl/.venv/lib/python3.13/site-packages/fastapi/dependencies/utils.py", line 293, in get_dependant
    param_details = analyze_param(
        param_name=param_name,
    ...<2 lines>...
        is_path_param=is_path_param,
    )
  File "/Users/tony/Projects/fastapi_exampl/.venv/lib/python3.13/site-packages/fastapi/dependencies/utils.py", line 510, in analyze_param
    is_scalar_field(field)
    ...<5 lines>...
    )
AssertionError
```

Stacktrace after:
```python
  File "/Users/tony/Projects/fastapi_exampl/.venv/lib/python3.13/site-packages/fastapi/dependencies/utils.py", line 293, in get_dependant
    param_details = analyze_param(
        param_name=param_name,
    ...<2 lines>...
        is_path_param=is_path_param,
    )
  File "/Users/tony/Projects/fastapi_exampl/.venv/lib/python3.13/site-packages/fastapi/dependencies/utils.py", line 510, in analyze_param
    is_scalar_field(field)
    ...<5 lines>...
    )
AssertionError: Query param 'data' must be of one of the supported types
```

Tool calls (0)