client an error.

                If `auto_error` is set to `False`, when the HTTP Basic authentication
                is not available, instead of erroring out, the dependency result will
                be `None`.

                This is useful when you want to have optional authentication.

                It is also useful when you want to have authentication that can be

                send the client an error.

                If `auto_error` is set to `False`, when the HTTP Authorization header
                is not available, instead of erroring out, the dependency result will
                be `None`.

                This is useful when you want to have optional authentication.

                It is also useful when you want to have authentication that can be

```

</div>

That command will generate code in `./src/client` and will use `axios` (the frontend HTTP library) internally.

### Try Out the Client Code

Now you can import and use the client code, it could look like this, notice that you get autocompletion for the methods:

<img src="/img/tutorial/generate-clients/image02.png">

    ```

=== "Python 3.8+"

    ```Python hl_lines="22"
    {!> ../../../docs_src/response_model/tutorial003.py!}
    ```

So, **FastAPI** will take care of filtering out all the data that is not declared in the output model (using Pydantic).

### `response_model` or Return Type

```

Mais maintenant, on déclare `q` avec `Query`, comme ceci :

```Python
q: Union[str, None] = Query(default=None, min_length=3)
```

Donc pour déclarer une valeur comme requise tout en utilisant `Query`, il faut utiliser `...` comme premier argument :

```Python hl_lines="7"
{!../../../docs_src/query_params_str_validations/tutorial006.py!}
```

!!! info

---

"_If you're looking to learn one **modern framework** for building REST APIs, check out **FastAPI** [...] It's fast, easy to use and easy to learn [...]_"

"_We've switched over to **FastAPI** for our **APIs** [...] I think you'll like it [...]_"

---

"_If you're looking to learn one **modern framework** for building REST APIs, check out **FastAPI** [...] It's fast, easy to use and easy to learn [...]_"

"_We've switched over to **FastAPI** for our **APIs** [...] I think you'll like it [...]_"

* Интерактивная документация API будет автоматически обновляться, включая новое тело:

![Swagger UI](https://fastapi.tiangolo.com/img/index/index-03-swagger-02.png)

* Нажмите на кнопку "Try it out", это позволит вам заполнить параметры и напрямую взаимодействовать с API:

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-04-swagger-03.png)

It uses the information from Webargs and Marshmallow to automatically generate OpenAPI schemas, using APISpec.

It's a great tool, very underrated. It should be way more popular than many Flask plug-ins out there. It might be due to its documentation being too concise and abstract.

This solved having to write YAML (another syntax) inside of Python docstrings.

* 交互式 API 文档将会自动更新，并加入新的请求体：

![Swagger UI](https://fastapi.tiangolo.com/img/index/index-03-swagger-02.png)

* 点击「Try it out」按钮，之后你可以填写参数并直接调用 API：

![Swagger UI interaction](https://fastapi.tiangolo.com/img/index/index-04-swagger-03.png)

* 然后点击「Execute」按钮，用户界面将会和 API 进行通信，发送参数，获取结果并在屏幕上展示：