But when you declare them with Python types (in the example above, as `int`), they are converted to that type and validated against it.

All the same process that applied for path parameters also applies for query parameters:

* Editor support (obviously)
* Data <dfn title="converting the string that comes from an HTTP request into Python data">"parsing"</dfn>
* Data validation
* Automatic documentation

Поскольку по умолчанию, отдельные значения интерпретируются как query-параметры, вам не нужно явно добавлять `Query`, вы можете просто сделать так:

```Python
q: str | None = None
```

Например:

{* ../../docs_src/body_multiple_params/tutorial004_an_py310.py hl[28] *}

/// info | Информация

一般來說，ASGI 中介軟體是類別，預期第一個參數接收一個 ASGI 應用程式。

因此，在第三方 ASGI 中介軟體的文件中，通常會指示你這樣做：

```Python
from unicorn import UnicornMiddleware

app = SomeASGIApp()

new_app = UnicornMiddleware(app, some_config="rainbow")
```

但 FastAPI（實際上是 Starlette）提供了一種更簡單的方式，確保內部中介軟體能處理伺服器錯誤，且自訂例外處理器可正常運作。

為此，你可以使用 `app.add_middleware()`（如同 CORS 範例）。

```Python
from fastapi import FastAPI
from unicorn import UnicornMiddleware

app = FastAPI()

Le code réel du callback dépendra fortement de votre application API.

Et il variera probablement beaucoup d’une application à l’autre.

Cela pourrait être seulement une ou deux lignes de code, comme :

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

///

此处唯一比较新的内容是*路径操作装饰器*中的 `callbacks=invoices_callback_router.routes` 参数，下文介绍。

## 存档回调 { #documenting-the-callback }

实际的回调代码高度依赖于您自己的 API 应用。

并且可能每个应用都各不相同。

回调代码可能只有一两行，比如：

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

但回调最重要的部分可能是，根据 API 要发送给回调请求体的数据等内容，确保您的 API 用户（外部开发者）正确地实现*外部 API*。

You can import them from `fastapi.security`:

```python
from fastapi.security import (
    APIKeyCookie,
    APIKeyHeader,
    APIKeyQuery,
    HTTPAuthorizationCredentials,
    HTTPBasic,
    HTTPBasicCredentials,
    HTTPBearer,
    HTTPDigest,
    OAuth2,

Imaginons que nous voulions avoir une dépendance qui vérifie si le paramètre de requête `q` contient un contenu fixe.

Mais nous voulons pouvoir paramétrer ce contenu fixe.

## Une instance « callable » { #a-callable-instance }

En Python, il existe un moyen de rendre une instance de classe « callable ».

Pas la classe elle‑même (qui est déjà un callable), mais une instance de cette classe.

Pour cela, nous déclarons une méthode `__call__` :

{* ../../docs_src/response_model/tutorial002_py310.py hl[7,9] *}

/// info

To use `EmailStr`, first install [`email-validator`](https://github.com/JoshData/python-email-validator).

Make sure you create a [virtual environment](../virtual-environments.md), activate it, and then install it, for example:

```console
$ pip install email-validator
```

or with:

{* ../../docs_src/response_model/tutorial002_py310.py hl[7,9] *}

/// info | Informação

Para usar `EmailStr`, primeiro instale [`email-validator`](https://github.com/JoshData/python-email-validator).

Certifique-se de criar um [ambiente virtual](../virtual-environments.md), ative-o e então instale-o, por exemplo:

```console
$ pip install email-validator
```

ou com:

```console

    Read more about it in the
    [FastAPI docs for Simple OAuth2 with Password and Bearer](https://fastapi.tiangolo.com/tutorial/security/simple-oauth2/).

    ## Example

    ```python
    from typing import Annotated

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

    app = FastAPI()


    @app.post("/login")