def __init__(
        self, app: ASGIApp, context_name: str = "fastapi_middleware_astack"
    ) -> None:
        self.app = app
        self.context_name = context_name

    async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
        async with AsyncExitStack() as stack:
            scope[self.context_name] = stack

    @property  # type: ignore
    def __class__(self):
        return uuid.UUID

    @property
    def __dict__(self):
        """Spoof a missing __dict__ by raising TypeError, this is how
        asyncpg.pgroto.pgproto.UUID behaves"""
        raise TypeError("vars() argument must have __dict__ attribute")


def test_pydanticv2():
    from pydantic import field_serializer

    app = FastAPI()

/// tip

因為 Pydantic 會在 **Rust** 端進行序列化，如果你有宣告回傳型別，效能會比未宣告時高很多。

///

### 非 async 的路徑操作函式 { #non-async-path-operation-functions }

你也可以使用一般的 `def` 函式（沒有 `async`），並同樣使用 `yield`。

FastAPI 會確保正確執行，不會阻塞事件迴圈。

由於此函式不是 async，正確的回傳型別是 `Iterable[Item]`：

{* ../../docs_src/server_sent_events/tutorial001_py310.py ln[28:31] hl[29] *}

### 無回傳型別 { #no-return-type }

@app.get("/items/{item_id}")
async def read_item(item_id: str):
    if item_id not in items:
        raise HTTPException(
            status_code=404,
            detail="Item not found",
            headers={"X-Error": "Some custom header"},
        )
    return {"item": items[item_id]}


@app.get("/http-no-body-statuscode-exception")
async def no_body_status_code_exception():

///

### Async Olmayan path operation function'lar { #non-async-path-operation-functions }

`async` olmadan normal `def` fonksiyonları da kullanabilir ve aynı şekilde `yield` yazabilirsiniz.

FastAPI, event loop’u bloklamayacak şekilde doğru çalışmasını garanti eder.

Bu durumda fonksiyon async olmadığı için doğru dönüş tipi `Iterable[Item]` olur:

router_default = APIRouter(prefix="/default")


@router_lax.post("/items/")
async def router_lax_post(data: dict):
    return data


@router_strict.post("/items/")
async def router_strict_post(data: dict):
    return data


@router_default.post("/items/")
async def router_default_post(data: dict):
    return data


app.include_router(router_lax)

from fastapi.testclient import TestClient
from typing_extensions import TypeAliasType


async def some_value() -> int:
    return 123


DependedValue = TypeAliasType(
    "DependedValue", Annotated[int, Depends(some_value)], type_params=()
)


def test_pep695_type_dependencies():
    app = FastAPI()

    @app.get("/")
    async def get_with_dep(value: DependedValue) -> str:  # noqa
        return f"value: {value}"

    description: str | None = None
    price: float
    tax: float | None = None
    tags: list[str] = []


@app.post("/items/", response_model=Item)
async def create_item(item: Item) -> Any:
    return item


@app.get("/items/", response_model=list[Item])
async def read_items() -> Any:
    return [
        {"name": "Portal Gun", "price": 42.0},
        {"name": "Plumbus", "price": 32.0},

}


@app.get(
    "/items/{item_id}/name",
    response_model=Item,
    response_model_include={"name", "description"},
)
async def read_item_name(item_id: str):
    return items[item_id]


@app.get("/items/{item_id}/public", response_model=Item, response_model_exclude={"tax"})
async def read_item_public_data(item_id: str):

* `close()`: Закрыть файл.

Поскольку все эти методы являются `async` методами, вам следует использовать "await" вместе с ними.

Например, внутри `async` *функции операции пути* можно получить содержимое с помощью:

```Python
contents = await myfile.read()
```