# Histoire, conception et avenir

Il y a quelque temps, <a href="https://github.com/fastapi/fastapi/issues/3#issuecomment-454956920" class="external-link" target="_blank">un utilisateur de **FastAPI** a demandé</a> :

> Quelle est l'histoire de ce projet ? Il semble être sorti de nulle part et est devenu génial en quelques semaines [...].

Voici un petit bout de cette histoire.

## Alternatives

**FastAPI** は`CommonQueryParams`クラスを呼び出します。これにより、そのクラスの「インスタンス」が作成され、インスタンスはパラメータ`commons`として関数に渡されます。

## 型注釈と`Depends`

上のコードでは`CommonQueryParams`を２回書いていることに注目してください:

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

以下にある最後の`CommonQueryParams`:

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

...は、**FastAPI** が依存関係を知るために実際に使用するものです。

from fastapi import Depends, FastAPI, Security
from fastapi.security import SecurityScopes
from fastapi.testclient import TestClient

app = FastAPI()


def get_user(required_scopes: SecurityScopes):
    return "john", required_scopes.scopes


def get_user_override(required_scopes: SecurityScopes):
    return "alice", required_scopes.scopes


def get_data():
    return [1, 2, 3]


def get_data_override():

from fastapi import Depends, FastAPI
from fastapi.security import HTTPBasic, HTTPBasicCredentials

app = FastAPI()

security = HTTPBasic()


@app.get("/users/me")
def read_current_user(credentials: HTTPBasicCredentials = Depends(security)):

from typing import Annotated

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: Annotated[str, Depends(oauth2_scheme)]):

import json
from typing import Annotated

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


def dependency_list() -> list[str]:
    return []


DepList = Annotated[list[str], Depends(dependency_list)]


def create_dependency(name: str):
    def fun(deps: DepList):
        deps.append(name)

    return Depends(fun)

from typing import Annotated

from fastapi import Depends, FastAPI

app = FastAPI()


def get_username():
    try:
        yield "Rick"
    finally:
        print("Cleanup up before response is sent")


@app.get("/users/me")
def get_user_me(username: Annotated[str, Depends(get_username, scope="function")]):

    client_tag: Optional[str] = Depends(_get_client_tag),
):
    return {"client_id": client_key, "client_tag": client_tag}


client = TestClient(app)

expected_schema = {
    "components": {
        "schemas": {
            "HTTPValidationError": {
                "properties": {
                    "detail": {
                        "items": {"$ref": "#/components/schemas/ValidationError"},

from typing import Annotated

from fastapi import Depends, FastAPI
from fastapi.security import HTTPBasic, HTTPBasicCredentials

app = FastAPI()

security = HTTPBasic()


@app.get("/users/me")
def read_current_user(credentials: Annotated[HTTPBasicCredentials, Depends(security)]):

from fastapi import Depends, FastAPI

app = FastAPI()


class FixedContentQueryChecker:
    def __init__(self, fixed_content: str):
        self.fixed_content = fixed_content

    def __call__(self, q: str = ""):
        if q:
            return self.fixed_content in q
        return False


checker = FixedContentQueryChecker("bar")


@app.get("/query-checker/")