# This is more or less a workaround to make Depends and Security hashable
# as other tools that use them depend on that
# Ref: https://github.com/fastapi/fastapi/pull/14320

from fastapi import Depends, Security


def dep():
    pass


def test_depends_hashable():
    dep()  # just for coverage
    d1 = Depends(dep)
    d2 = Depends(dep)
    d3 = Depends(dep, scope="function")
    d4 = Depends(dep, scope="function")

):
    return await instance(value)


@app.get("/async-callable-gen-dependency-class")
async def get_async_callable_gen_dependency_class(
    value: str, instance: AsyncCallableGenDependency = Depends()
):
    return await instance(value).__anext__()


@app.get("/callable-dependency")
async def get_callable_dependency(value: str = Depends(callable_dependency)):
    return value

# Dependencies - `Depends()` and `Security()`

## `Depends()`

Dependencies are handled mainly with the special function `Depends()` that takes a callable.

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

**FastAPI** 调用 `CommonQueryParams` 类。这将创建该类的一个 "实例"，该实例将作为参数 `commons` 被传递给你的函数。

## 类型注解 vs `Depends`

注意，我们在上面的代码中编写了两次`CommonQueryParams`：

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

最后的 `CommonQueryParams`:

```Python
... = Depends(CommonQueryParams)
```

...实际上是 **Fastapi** 用来知道依赖项是什么的。

FastAPI 将从依赖项中提取声明的参数，这才是 FastAPI 实际调用的。

    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)
    if not user_dict:

```

////

//// tab | Python 3.9+ non-Annotated

/// tip

Prefer to use the `Annotated` version if possible.

///

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

////

You declare the dependency as the type of the parameter, and you use `Depends()` without any parameter, instead of having to write the full class *again* inside of `Depends(CommonQueryParams)`.

```

////

//// tab | Python 3.9+ non-Annotated

/// tip | Dica

Utilize a versão com `Annotated` se possível.

///

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

////

Você declara a dependência como o tipo do parâmetro, e utiliza `Depends()` sem nenhum parâmetro, em vez de ter que escrever a classe *novamente* dentro de `Depends(CommonQueryParams)`.

    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

**FastAPI**는 `CommonQueryParams` 클래스를 호출합니다. 이것은 해당 클래스의 "인스턴스"를 생성하고 그 인스턴스는 함수의 매개변수 `commons`로 전달됩니다.

## 타입 힌팅 vs `Depends`

위 코드에서 `CommonQueryParams`를 두 번 작성한 방식에 주목하십시오:

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

마지막 `CommonQueryParams` 변수를 보면:

```Python
... = Depends(CommonQueryParams)
```

... **FastAPI**가 실제로 어떤 것이 의존성인지 알기 위해서 사용하는 방법입니다.

        return foo

    with pytest.raises(
        AssertionError,
        match=(
            "Cannot specify `Depends` in `Annotated` and default value"
            " together for 'foo'"
        ),
    ):

        @app.get("/")
        async def get2(foo: Annotated[int, Depends(dep)] = Depends(dep)):
            pass  # pragma: nocover

    with pytest.raises(
        AssertionError,
        match=(