{!../../../docs_src/query_params_str_validations/tutorial005.py!}
```

!!! note "Rappel"
    Avoir une valeur par défaut rend le paramètre optionnel.

## Rendre ce paramètre requis

Quand on ne déclare ni validation, ni métadonnée, on peut rendre le paramètre `q` requis en ne lui déclarant juste aucune valeur par défaut :

```Python
q: str
```

à la place de :

```Python
q: Union[str, None] = None
```

* **de la vérification de types**

...et **FastAPI** utilise ces mêmes déclarations pour :

* **Définir les prérequis** : depuis les paramètres de chemins des requêtes, les entêtes, les corps, les dépendances, etc.
* **Convertir des données** : depuis la requête vers les types requis.
* **Valider des données** : venant de chaque requête :
    * Générant automatiquement des **erreurs** renvoyées au client quand la donnée est invalide.

    }

    internal constructor(request: Request) {
      this.url = request.url
      this.method = request.method
      this.body = request.body
      this.tags =
        when {
          request.tags.isEmpty() -> mapOf()
          else -> request.tags.toMutableMap()
        }
      this.headers = request.headers.newBuilder()
      this.cacheUrlOverride = request.cacheUrlOverride
    }

    {!> ../../../docs_src/request_files/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="1"
    {!> ../../../docs_src/request_files/tutorial001_an.py!}
    ```

=== "Python 3.8+ non-Annotated"

    !!! tip
        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="1"
    {!> ../../../docs_src/request_files/tutorial001.py!}
    ```

  }

  companion object {
    /**
     * Cache control request directives that require network validation of responses. Note that such
     * requests may be assisted by the cache via conditional GET requests.
     */
    @JvmField
    val FORCE_NETWORK = commonForceNetwork()

    /**
     * Cache control request directives that uses the cache only, even if the cached response is

pull requests are approved and pass continuous integration checks, a TensorFlow
team member will apply `ready to pull` label to your change. This means we are
working on getting your pull request submitted to our internal repository. After
the change has been submitted internally, your pull request will be merged
automatically on GitHub.

If you want to contribute, start working through the TensorFlow codebase,
navigate to the

  val millis = unit.toMillis(duration)
  require(millis <= Integer.MAX_VALUE) { "$name too large" }
  require(millis != 0L || duration <= 0L) { "$name too small" }
  return millis.toInt()
}

internal fun checkDuration(
  name: String,
  duration: Duration,
): Int {
  check(!duration.isNegative()) { "$name < 0" }
  val millis = duration.inWholeMilliseconds
  require(millis <= Integer.MAX_VALUE) { "$name too large" }

We also declare a special parameter of type `SecurityScopes`, imported from `fastapi.security`.

This `SecurityScopes` class is similar to `Request` (`Request` was used to get the request object directly).

=== "Python 3.10+"

    ```Python hl_lines="8  105"
    {!> ../../../docs_src/security/tutorial005_an_py310.py!}
    ```

=== "Python 3.9+"

    flags: Int,
  ) {
    if (type != TYPE_WINDOW_UPDATE && logger.isLoggable(FINE)) {
      logger.fine(frameLog(false, streamId, length, type, flags))
    }
    require(length <= maxFrameSize) { "FRAME_SIZE_ERROR length > $maxFrameSize: $length" }
    require(streamId and 0x80000000.toInt() == 0) { "reserved bit set: $streamId" }
    sink.writeMedium(length)
    sink.writeByte(type and 0xff)
    sink.writeByte(flags and 0xff)

---

Common examples of CPU bound operations are things that require complex math processing.

For example:

* **Audio** or **image processing**.
* **Computer vision**: an image is composed of millions of pixels, each pixel has 3 values / colors, processing that normally requires computing something on those pixels, all at the same time.