```Python
q: Union[str, None] = Query(default=None, max_length=50)
```

Cela va valider les données, montrer une erreur claire si ces dernières ne sont pas valides, et documenter le paramètre dans le schéma `OpenAPI` de cette *path operation*.

## Rajouter plus de validation

Vous pouvez aussi rajouter un second paramètre `min_length` :

OkHttp Server-Sent Events
=========================

Experimental support for server-sent events.
API is not considered stable and may change at any time.

### Download

```kotlin
testImplementation("com.squareup.okhttp3:okhttp-sse:5.3.0")

async def create_file(file: Annotated[bytes | None, File()] = None):
    if not file:
        return {"message": "No file sent"}
    else:
        return {"file_size": len(file)}


@app.post("/uploadfile/")
async def create_upload_file(file: UploadFile | None = None):
    if not file:
        return {"message": "No upload file sent"}
    else:

    client.webSocket!!.finishReader()
    taskFaker.runTasks()
    assertThat(client.closed).isTrue()
    client.listener.assertFailure(
      ProtocolException::class.java,
      "Server-sent frames must not be masked.",
    )
    server.listener.assertClosing(1000, "Hello")
    server.listener.assertExhausted() // Client should not have sent second close.
  }

  @Test

    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

    */
    int NTLMSSP_NEGOTIATE_ALWAYS_SIGN = 0x00008000;

    /**
    * Sent by the server in the Type 2 message to indicate that the
    * target authentication realm is a domain.
    */
    int NTLMSSP_TARGET_TYPE_DOMAIN = 0x00010000;

    /**
    * Sent by the server in the Type 2 message to indicate that the
    * target authentication realm is a server.
    */

     *
     * @param primary true if primary
     */
    public void setPrimary(boolean primary) {
        this.isPrimary = primary;
    }

    /**
     * Get number of bytes sent
     *
     * @return bytes sent
     */
    public long getBytesSent() {
        return bytesSent.get();
    }

    /**
     * Get number of bytes received
     *
     * @return bytes received
     */

        return {"message": "Notification sent in the background"}
    ```
    """

    def add_task(
        self,
        func: Annotated[
            Callable[P, Any],
            Doc(
                """
                The function to call after the response is sent.

                It can be a regular `def` function or an `async def` function.
                """

```
http://127.0.0.1:8000/items/?skip=0&limit=10
```

...les paramètres de requête sont :

* `skip` : avec une valeur de`0`
* `limit` : avec une valeur de `10`

Faisant partie de l'URL, ces valeurs sont des chaînes de caractères (`str`).

Mais quand on les déclare avec des types Python (dans l'exemple précédent, en tant qu'`int`), elles sont converties dans les types renseignés.

    if not file:
        return {"message": "No file sent"}
    else:
        return {"file_size": len(file)}


@app.post("/uploadfile/")
async def create_upload_file(file: Union[UploadFile, None] = None):
    if not file:
        return {"message": "No upload file sent"}
    else: