By default, if no HTTP Authorization header is provided, required for
                OAuth2 authentication, it will automatically cancel the request and
                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`.

You will also get autocompletion for the payload to send:

<img src="/img/tutorial/generate-clients/image03.png">

!!! tip
    Notice the autocompletion for `name` and `price`, that was defined in the FastAPI application, in the `Item` model.

You will have inline errors for the data that you send:

<img src="/img/tutorial/generate-clients/image04.png">

In that case, it would mean the JSON attributes, and data types they have, etc.

#### OpenAPI and JSON Schema

OpenAPI defines an API schema for your API. And that schema includes definitions (or "schemas") of the data sent and received by your API using **JSON Schema**, the standard for JSON data schemas.

#### Check the `openapi.json`

  "full_name": "John Doe",
  "disabled": false
}
```

<img src="/img/tutorial/security/image09.png">

If you open the developer tools, you could see how the data sent only includes the token, the password is only sent in the first request to authenticate the user and get that access token, but not afterwards:

<img src="/img/tutorial/security/image10.png">

!!! note

One of the main features needed by API systems is data "<abbr title="also called marshalling, conversion">serialization</abbr>" which is taking data from the code (Python) and converting it into something that can be sent through the network. For example, converting an object containing data from a database into a JSON object. Converting `datetime` objects into strings, etc.

### HTTP Response

The application would process the request and send a **plain (unencrypted) HTTP response** to the TLS Termination Proxy.

<img src="/img/deployment/https/https06.svg">

### HTTPS Response

The TLS Termination Proxy would then **encrypt the response** using the cryptography agreed before (that started with the certificate for `someapp.example.com`), and send it back to the browser.

    Note over client,operation: Response is already sent, can't change it anymore
    opt Tasks
        operation -->> tasks: Send background tasks
    end
    opt Raise other exception
        tasks -->> tasks: Handle exceptions in the background task code
    end
```

!!! info

    E.g. `pip install python-multipart`.

    This is because uploaded files are sent as "form data".

## Import `File`

Import `File` and `UploadFile` from `fastapi`:

=== "Python 3.9+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/request_files/tutorial001_an_py39.py!}
    ```

```

Comme nous devons remplacer la valeur par défaut `None` dans la fonction par `Query()`, nous pouvons maintenant définir la valeur par défaut avec le paramètre `Query(default=None)`, il sert le même objectif qui est de définir cette valeur par défaut.

Donc :

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

... rend le paramètre optionnel, et est donc équivalent à :

```Python

                """
                By default, if the HTTP Basic authentication is not provided (a
                header), `HTTPBasic` will automatically cancel the request and send the
                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`.