BrokenSessionDep = Annotated[Session, Depends(broken_dep_session)]

app = FastAPI()


@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket, session: SessionDep):
    await websocket.accept()
    for item in session:
        await websocket.send_text(f"{item}")


@app.websocket("/ws-broken")
async def websocket_endpoint_broken(websocket: WebSocket, session: BrokenSessionDep):
    await websocket.accept()

# Without aliases


@app.get("/optional-str")
async def read_optional_str(p: Annotated[str | None, Cookie()] = None):
    return {"p": p}


class CookieModelOptionalStr(BaseModel):
    p: str | None = None


@app.get("/model-optional-str")
async def read_model_optional_str(p: Annotated[CookieModelOptionalStr, Cookie()]):
    return {"p": p.p}

/**
 * termynal.js
 * A lightweight, modern and extensible animated terminal window, using
 * async/await.
 *
 * @author Ines Montani <******@****.***>
 * @version 0.0.1
 * @license MIT
 */

'use strict';

/** Generate a terminal widget. */
class Termynal {
    /**
     * Construct the widget's settings.
     * @param {(string|Node)=} container - Query selector or container element.
     * @param {Object=} options - Custom settings.

                input.value = ''
                event.preventDefault()
            }
        </script>
    </body>
</html>
"""


@app.get("/")
async def get():
    return HTMLResponse(html)


@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        data = await websocket.receive_text()

@app.get("/items/{item_id}", response_model=Item)
async def read_main(item_id: str, x_token: str = Header()):
    if x_token != fake_secret_token:
        raise HTTPException(status_code=400, detail="Invalid X-Token header")
    if item_id not in fake_db:
        raise HTTPException(status_code=404, detail="Item not found")
    return fake_db[item_id]


@app.post("/items/")
async def create_item(item: Item, x_token: str = Header()) -> Item:

/// tip | 提示

由于 Pydantic 会在**Rust** 端序列化它，相比未声明返回类型，你将获得更高的**性能**。

///

### 非 async 的*路径操作函数* { #non-async-path-operation-functions }

你也可以使用常规的 `def` 函数（没有 `async`），并以同样的方式使用 `yield`。

FastAPI 会确保其正确运行，从而不阻塞事件循环。

由于此时函数不是 async，正确的返回类型应为 `Iterable[Item]`：

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

### 无返回类型 { #no-return-type }

# Without aliases


@app.get("/optional-list-str")
async def read_optional_list_str(
    p: Annotated[list[str] | None, Header()] = None,
):
    return {"p": p}


class HeaderModelOptionalListStr(BaseModel):
    p: list[str] | None = None


@app.get("/model-optional-list-str")
async def read_model_optional_list_str(
    p: Annotated[HeaderModelOptionalListStr, Header()],
):

        return HTTPException(
            status_code=HTTP_401_UNAUTHORIZED,
            detail="Not authenticated",
            headers=self.make_authenticate_headers(),
        )

    async def __call__(self, request: Request) -> HTTPAuthorizationCredentials | None:
        authorization = request.headers.get("Authorization")
        scheme, credentials = get_authorization_scheme_param(authorization)

        statusField.setInt(smb, status);
    }

    private void setAsync(ServerMessageBlock2 smb, boolean async) throws Exception {
        Field asyncField = ServerMessageBlock2.class.getDeclaredField("async");
        asyncField.setAccessible(true);
        asyncField.setBoolean(smb, async);
    }

app = FastAPI()


def get_db():
    db = DBSession()
    try:
        yield db
    finally:
        db.close()


DBDep = Annotated[DBSession, Depends(get_db)]


@app.get("/items/")
async def read_items(db: DBDep):
    return db.query(Item).all()
```

Use the scope `"function"` when they should run the exit code after the response data is generated but before the response is sent back to the client.