# Templates { #templates }

Você pode usar qualquer template engine com o **FastAPI**.

Uma escolha comum é o Jinja2, o mesmo usado pelo Flask e outras ferramentas.

Existem utilitários para configurá-lo facilmente que você pode usar diretamente em sua aplicação **FastAPI** (fornecidos pelo Starlette).

## Instalar dependências { #install-dependencies }

You can import it from `fastapi.requests`:

```python
from fastapi.requests import HTTPConnection
```

而且有許多替代方案，所有這些都是基於 OpenAPI。你可以輕鬆地將任何這些替代方案添加到使用 **FastAPI** 建置的應用程式中。

你也可以用它自動生成程式碼，讓前端、手機應用程式或物聯網設備等與你的 API 進行通訊。

## 逐步回顧

### 第一步：引入 `FastAPI`

{* ../../docs_src/first_steps/tutorial001.py h1[1] *}

`FastAPI` 是一個 Python 類別，提供所有 API 的全部功能。

/// note | Technical Details

`FastAPI` 是一個直接繼承自 `Starlette` 的類別。

```Dockerfile
FROM python:3.7

RUN pip install fastapi uvicorn

EXPOSE 80

COPY ./app /app

CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "80"]
```

## Créer le code **FastAPI**.

* Créer un répertoire `app` et y entrer.
* Créez un fichier `main.py` avec :

```Python
from typing import Optional

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():

from typing import Optional

from fastapi import Depends, FastAPI, Security
from fastapi.security import APIKeyQuery
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

api_key = APIKeyQuery(name="key", auto_error=False)


class User(BaseModel):
    username: str


def get_current_user(oauth_header: Optional[str] = Security(api_key)):
    if oauth_header is None:
        return None

from fastapi import FastAPI, Security
from fastapi.security import HTTPAuthorizationCredentials, HTTPDigest
from fastapi.testclient import TestClient

app = FastAPI()

security = HTTPDigest()


@app.get("/users/me")
def read_current_user(credentials: HTTPAuthorizationCredentials = Security(security)):
    return {"scheme": credentials.scheme, "credentials": credentials.credentials}


client = TestClient(app)

from typing import Optional

from fastapi import Depends, FastAPI, Security
from fastapi.security import APIKeyCookie
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

api_key = APIKeyCookie(name="key", auto_error=False)


class User(BaseModel):
    username: str


def get_current_user(oauth_header: Optional[str] = Security(api_key)):
    if oauth_header is None:
        return None

import pytest
from fastapi import FastAPI
from fastapi.testclient import TestClient


@pytest.fixture(name="app", scope="module")
def get_app():
    with pytest.warns(DeprecationWarning):
        from docs_src.events.tutorial001_py39 import app
    yield app


def test_events(app: FastAPI):
    with TestClient(app) as client:
        response = client.get("/items/foo")
        assert response.status_code == 200, response.text

### Filtrado de Datos en FastAPI { #fastapi-data-filtering }

Ahora, para FastAPI, verá el tipo de retorno y se asegurará de que lo que devuelves incluya **solo** los campos que están declarados en el tipo.

from typing import Union

from fastapi import FastAPI, Path, Query

app = FastAPI()


@app.get("/items/{item_id}")
async def read_items(
    item_id: int = Path(title="The ID of the item to get"),
    q: Union[str, None] = Query(default=None, alias="item-query"),
):
    results = {"item_id": item_id}
    if q:
        results.update({"q": q})