### Dosyalar ve Async { #files-and-async }

Çoğu durumda dosya benzeri nesneler, varsayılan olarak async ve await ile uyumlu değildir.

Örneğin, `await file.read()` ya da `async for chunk in file` gibi şeyler yoktur.

        @app.get("/items/{item_id}/")
        async def get_item(item_id: Annotated[int, Path(default=1)]):
            pass  # pragma: nocover

    with pytest.raises(
        AssertionError,
        match=(
            "`Query` default value cannot be set in `Annotated` for 'item_id'. Set the"
            " default value with `=` instead."
        ),
    ):

        @app.get("/")

        monkeypatch.delattr("multipart.multipart.parse_options_header", raising=False)
    with pytest.raises(RuntimeError, match=multipart_incorrect_install_error):
        app = FastAPI()

        @app.post("/")
        async def root(username: str = Form()):
            return username  # pragma: nocover


def test_incorrect_multipart_installed_file_upload(monkeypatch):
    monkeypatch.setattr("python_multipart.__version__", "0.0.12")

## Async vs Sync *path operations*

Use `async` *path operations* only when fully certain that the logic called inside is compatible with async and await (it's called with `await`) or that doesn't block.

```python
from fastapi import FastAPI

app = FastAPI()


# Use async def when calling async code
@app.get("/async-items/")
async def read_async_items():

    @app.post("/files/")
    async def create_file(file: Annotated[bytes, File()]):
        return {"file_size": len(file)}


    @app.post("/uploadfile/")
    async def create_upload_file(file: UploadFile):
        return {"filename": file.filename}
    ```
    """

    file: Annotated[
        BinaryIO,
        Doc("The standard Python file object (non-async)."),
    ]

    media_type = "image/png"


@app.get("/image/stream", response_class=PNGStreamingResponse)
async def stream_image() -> AsyncIterable[bytes]:
    with read_image() as image_file:
        for chunk in image_file:
            yield chunk


@app.get("/image/stream-no-async", response_class=PNGStreamingResponse)
def stream_image_no_async() -> Iterable[bytes]:
    with read_image() as image_file:

counter_holder = {"counter": 0}


async def dep_counter():
    counter_holder["counter"] += 1
    return counter_holder["counter"]


async def super_dep(count: int = Depends(dep_counter)):
    return count


@app.get("/counter/")
async def get_counter(count: int = Depends(dep_counter)):
    return {"counter": count}


@app.get("/sub-counter/")
async def get_sub_counter(

	lockRPCRUnlock     = newLockHandler(grid.HandlerLockRUnlock)
)

func newLockHandler(h grid.HandlerID) *grid.SingleHandler[*dsync.LockArgs, *dsync.LockResp] {
	return grid.NewSingleHandler[*dsync.LockArgs, *dsync.LockResp](h, func() *dsync.LockArgs {
		return &dsync.LockArgs{}
	}, func() *dsync.LockResp {
		return &dsync.LockResp{}
	})
}

// registerLockRESTHandlers - register lock rest router.

def test_merged_mixed_state_lifespans() -> None:
    @asynccontextmanager
    async def lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
        yield

    @asynccontextmanager
    async def router_lifespan(app: FastAPI) -> AsyncGenerator[dict[str, bool], None]:
        yield {"router": True}

    @asynccontextmanager
    async def sub_router_lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
        yield

async def stream_story_no_annotation():
    for line in message.splitlines():
        yield line


@app.get("/story/stream-no-async-no-annotation", response_class=StreamingResponse)
def stream_story_no_async_no_annotation():
    for line in message.splitlines():
        yield line


@app.get("/story/stream-bytes", response_class=StreamingResponse)