] = None,
    max_length: Annotated[
        Optional[int],
        Doc(
            """
            Maximum length for strings.
            """
        ),
    ] = None,
    pattern: Annotated[
        Optional[str],
        Doc(
            """
            RegEx pattern for strings.
            """
        ),
    ] = None,
    regex: Annotated[
        Optional[str],
        Doc(

        security_scopes: SecurityScopes,
        db_session: Annotated[str, Depends(get_db_session)],
    ):
        call_counts["get_current_user"] += 1
        return {
            "user": f"user_{call_counts['get_current_user']}",
            "scopes": security_scopes.scopes,
            "db_session": db_session,
        }

    def get_user_me(
        current_user: Annotated[dict, Security(get_current_user, scopes=["me"])],
    ):

Beachten Sie, wie wir `CommonQueryParams` im obigen Code zweimal schreiben:

//// tab | Python 3.9+

```Python
commons: Annotated[CommonQueryParams, Depends(CommonQueryParams)]
```

////

//// tab | Python 3.9+ nicht annotiert

/// tip | Tipp

Bevorzugen Sie die `Annotated`-Version, falls möglich.

///

```Python
commons: CommonQueryParams = Depends(CommonQueryParams)
```

////

    ## Example

    ```python
    from typing import Annotated

    from fastapi import Depends, FastAPI
    from fastapi.security import OAuth2PasswordRequestForm

    app = FastAPI()


    @app.post("/login")
    def login(form_data: Annotated[OAuth2PasswordRequestForm, Depends()]):
        data = {}
        data["scopes"] = []

            return func

        return decorator

    def include_router(
        self,
        router: Annotated["APIRouter", Doc("The `APIRouter` to include.")],
        *,
        prefix: Annotated[str, Doc("An optional path prefix for the router.")] = "",
        tags: Annotated[
            Optional[list[Union[str, Enum]]],
            Doc(
                """

    yield s
    s.open = False
    global_state = global_context.get()
    global_state["session_closed"] = True


SessionFuncDep = Annotated[Session, Depends(dep_session, scope="function")]
SessionRequestDep = Annotated[Session, Depends(dep_session, scope="request")]
SessionDefaultDep = Annotated[Session, Depends(dep_session)]


class NamedSession:
    def __init__(self, name: str = "default") -> None:
        self.name = name

Make sure you [Upgrade the FastAPI version](../deployment/versions.md#upgrading-the-fastapi-versions){.internal-link target=_blank} to at least 0.95.1 before using `Annotated`.

///

## Use `Annotated` in the type for the `q` parameter { #use-annotated-in-the-type-for-the-q-parameter }

    yield
    raise HTTPException(status_code=503, detail="Exception after yield")


SessionFuncDep = Annotated[Session, Depends(dep_session, scope="function")]
SessionRequestDep = Annotated[Session, Depends(dep_session, scope="request")]
SessionDefaultDep = Annotated[Session, Depends(dep_session)]


class NamedSession:
    def __init__(self, name: str = "default") -> None:
        self.name = name

        )
    return user


async def get_current_active_user(
    current_user: Annotated[User, Depends(get_current_user)],
):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user


@app.post("/token")
async def login(form_data: Annotated[OAuth2PasswordRequestForm, Depends()]):
    user_dict = fake_users_db.get(form_data.username)

from typing import Annotated, Optional

import pytest
from fastapi import FastAPI, Header
from fastapi.testclient import TestClient
from pydantic import BaseModel, Field

app = FastAPI()

# =====================================================================================
# Without aliases


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