from typing import Annotated, Any
from unittest.mock import Mock, patch

from fastapi import Depends, FastAPI
from fastapi.testclient import TestClient

from docs_src.dependencies.tutorial010_py39 import get_db


def test_get_db():
    app = FastAPI()

    @app.get("/")
    def read_root(c: Annotated[Any, Depends(get_db)]):
        return {"c": str(c)}

    client = TestClient(app)

    dbsession_mock = Mock()

from fastapi import Depends, FastAPI, HTTPException

app = FastAPI()


class InternalError(Exception):
    pass


def get_username():
    try:
        yield "Rick"
    except InternalError:
        print("Oops, we didn't raise again, Britney 😱")


@app.get("/items/{item_id}")
def get_item(item_id: str, username: str = Depends(get_username)):
    if item_id == "portal-gun":
        raise InternalError(

**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.

from typing import Annotated

from fastapi import Depends, FastAPI

app = FastAPI()


fake_items_db = [{"item_name": "Foo"}, {"item_name": "Bar"}, {"item_name": "Baz"}]


class CommonQueryParams:
    def __init__(self, q: str | None = None, skip: int = 0, limit: int = 100):
        self.q = q
        self.skip = skip
        self.limit = limit


@app.get("/items/")

В версии 0.121.0 FastAPI добавил поддержку `Depends(scope="function")` для зависимостей с `yield`.

При использовании `Depends(scope="function")` код после `yield` выполняется сразу после завершения *функции-обработчика пути*, до отправки ответа клиенту.

А при использовании `Depends(scope="request")` (значение по умолчанию) код после `yield` выполняется после отправки ответа.

from typing import Annotated

from fastapi import BackgroundTasks, Depends, FastAPI

app = FastAPI()


def write_log(message: str):
    with open("log.txt", mode="a") as log:
        log.write(message)


def get_query(background_tasks: BackgroundTasks, q: str | None = None):
    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q

from typing import Union

from fastapi import BackgroundTasks, Depends, FastAPI

app = FastAPI()


def write_log(message: str):
    with open("log.txt", mode="a") as log:
        log.write(message)


def get_query(background_tasks: BackgroundTasks, q: Union[str, None] = None):
    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q

`Security` ist tatsächlich eine Unterklasse von `Depends` und hat nur noch einen zusätzlichen Parameter, den wir später kennenlernen werden.

Durch die Verwendung von `Security` anstelle von `Depends` weiß **FastAPI** jedoch, dass es Sicherheits-Scopes deklarieren, intern verwenden und die API mit OpenAPI dokumentieren kann.

from typing import Annotated

from fastapi import Depends, FastAPI, HTTPException

app = FastAPI()


data = {
    "plumbus": {"description": "Freshly pickled plumbus", "owner": "Morty"},
    "portal-gun": {"description": "Gun to create portals", "owner": "Rick"},
}


class OwnerError(Exception):
    pass


def get_username():
    try:
        yield "Rick"
    except OwnerError as e:

from fastapi import Depends, FastAPI
from fastapi.security import OAuth2PasswordBearer

app = FastAPI()

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")


@app.get("/items/")
async def read_items(token: str = Depends(oauth2_scheme)):