Merging this PR will not alter performance

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Comparing musicinmybrain:starlette-0.51 (cd01810) with master (79406a4)

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Last commit cd01810 at: https://992b0e89.fastapitiangolo.pages.dev

Could we get this bumped to <0.53 as 0.52.1 is out. https://github.com/Kludex/starlette/releases/tag/0.52.1

Could we get this bumped to <0.53 as 0.52.1 is out. https://github.com/Kludex/starlette/releases/tag/0.52.1

Sure. It looks like 0.52.0 should be compatible, and just adds a new feature: “In this release, State can be accessed using dictionary-style syntax for improved type safety (https://github.com/Kludex/starlette/pull/3036).”

Updated to allow Starlette 0.52. All tests still pass.

Failing CI should be resolved by #14756

This pull request has a merge conflict that needs to be resolved.

Will this allow using strict types for app.state?

Will this allow using strict types for app.state?

I have no idea. I suppose you must be talking about the changes in https://github.com/Kludex/starlette/releases/tag/0.52.0.

Will this allow using strict types for app.state?

It does not seem to work... I took the Starlette docs example, converted it to use FastAPI and forced an installation of starlette==0.52.1. Have pasted the stack trace below.

from collections.abc import AsyncIterator
from contextlib import asynccontextmanager
from typing import TypedDict

import httpx
from fastapi import FastAPI, Request
from fastapi.responses import PlainTextResponse


class State(TypedDict):
    http_client: httpx.AsyncClient


@asynccontextmanager
async def lifespan(app: FastAPI) -> AsyncIterator[State]:
    async with httpx.AsyncClient() as client:
        yield {"http_client": client}


app = FastAPI(lifespan=lifespan)


@app.get("/")
async def homepage(request: Request[State]) -> PlainTextResponse:
    client = request.state["http_client"]

    reveal_type(client)  # Revealed type is 'httpx.AsyncClient'

    response = await client.get("https://www.example.com")
    return PlainTextResponse(response.text)


if __name__ == "__main__":
    import uvicorn

    uvicorn.run(app=app)

Traceback (most recent call last):
  File "/Users/ollie/Documents/fastapi-lifespan-state-attribute-style.py", line 24, in <module>
    @app.get("/")
     ~~~~~~~^^^^^
  File "/Users/ollie/Documents/.venv/lib/python3.13/site-packages/fastapi/routing.py", line 1063, in decorator
    self.add_api_route(
    ~~~~~~~~~~~~~~~~~~^
        path,
        ^^^^^
    ...<23 lines>...
        generate_unique_id_function=generate_unique_id_function,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/ollie/Documents/.venv/lib/python3.13/site-packages/fastapi/routing.py", line 1002, in add_api_route
    route = route_class(
        self.prefix + path,
    ...<24 lines>...
        generate_unique_id_function=current_generate_unique_id,
    )
  File "/Users/ollie/Documents/.venv/lib/python3.13/site-packages/fastapi/routing.py", line 621, in __init__
    self.dependant = get_dependant(
                     ~~~~~~~~~~~~~^
        path=self.path_format, call=self.endpoint, scope="function"
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/ollie/Documents/.venv/lib/python3.13/site-packages/fastapi/dependencies/utils.py", line 281, in get_dependant
    param_details = analyze_param(
        param_name=param_name,
    ...<2 lines>...
        is_path_param=is_path_param,
    )
  File "/Users/ollie/Documents/.venv/lib/python3.13/site-packages/fastapi/dependencies/utils.py", line 506, in analyze_param
    field = create_model_field(
        name=param_name,
    ...<4 lines>...
        field_info=field_info,
    )
  File "/Users/ollie/Documents/.venv/lib/python3.13/site-packages/fastapi/utils.py", line 95, in create_model_field
    raise fastapi.exceptions.FastAPIError(
        _invalid_args_message.format(type_=type_)
    ) from None
fastapi.exceptions.FastAPIError: Invalid args for response field! Hint: check that starlette.requests.Request[__main__.State] is a valid Pydantic field type. If you are using a return type annotation that is not a valid Pydantic field (e.g. Union[Response, dict, None]) you can disable generating the response model from the type annotation with the path operation decorator parameter response_model=None. Read more: https://fastapi.tiangolo.com/tutorial/response-model/

The above implies more changes are needed than just the bump. 😢

Will this allow using strict types for app.state?

It does not seem to work... I took the Starlette docs example, converted it to use FastAPI and forced an installation of starlette==0.52.1. Have pasted the stack trace below.

Thanks. Does this imply we need FastAPI changes to make it work, or further Starlette?

FastAPI.

FastAPI.

Thank you, I'll be happy to contribute this change once this PR is merged, if needed.

With #14756 in and CI all green, is there anything else blocking this PR @YuriiMotov?

Hi! Bumping this too, we need the updates to CORSMiddleware introduced in Starlette 0.51.0 and current constraints are blocking us from this.

This pull request has a merge conflict that needs to be resolved.

I guess this is now superseded by #14853

This was superseded by #14853, released in FastAPI 0.128.3 🎉

I fixed what is needed to support the latest Starlette version, and what is in git in the main branch in another PR. 🤓

I fixed what is needed to support the latest Starlette version, and what is in git in the main branch in another PR. 🤓

@tiangolo Can I clarify if here you were referring to starlette 0.52.0+ Request with generic state type? I just tried 0.128.3 and the example shown above still errors in the same way.

This was superseded by #14853, released in FastAPI 0.128.3 🎉

Thank you! The broader version range will be quite helpful for downstream packaging.