**Note:** We use `int | None` for the primary key field so that in Python code we can *create an object without an `id`* (`id=None`), assuming the database will *generate it when saving*. SQLModel understands that the database will provide the `id` and *defines the column as a non-null `INTEGER`* in the database schema. See <a href="https://sqlmodel.tiangolo.com/tutorial/create-db-and-table/#primary-key-id" class="external-link" target="_blank">SQLModel docs on primary keys</a> for details.

* `Field(index=True)`...

  public static final MediaType WEBM_AUDIO = createConstant(AUDIO_TYPE, "webm");

  /**
   * L16 audio, as defined by <a href="https://tools.ietf.org/html/rfc2586">RFC 2586</a>.
   *
   * @since 24.1
   */
  public static final MediaType L16_AUDIO = createConstant(AUDIO_TYPE, "l16");

  /**
   * L24 audio, as defined by <a href="https://tools.ietf.org/html/rfc3190">RFC 3190</a>.
   *
   * @since 20.0
   */

{* ../../docs_src/query_params_str_validations/tutorial006c_an_py310.py hl[9] *}

## Lista de parámetros de Query / múltiples valores { #query-parameter-list-multiple-values }

Cuando defines un parámetro de query explícitamente con `Query` también puedes declararlo para recibir una lista de valores, o dicho de otra manera, para recibir múltiples valores.

   *
   * <p><b>Java 8+ users:</b> this class is now obsolete as explained in the class documentation, so
   * there is no need to use this method.
   *
   * @param comparator the comparator that defines the order
   * @return comparator itself if it is already an {@code Ordering}; otherwise an ordering that
   *     wraps that comparator
   */

  public static final MediaType WEBM_AUDIO = createConstant(AUDIO_TYPE, "webm");

  /**
   * L16 audio, as defined by <a href="https://tools.ietf.org/html/rfc2586">RFC 2586</a>.
   *
   * @since 24.1
   */
  public static final MediaType L16_AUDIO = createConstant(AUDIO_TYPE, "l16");

  /**
   * L24 audio, as defined by <a href="https://tools.ietf.org/html/rfc3190">RFC 3190</a>.
   *
   * @since 20.0
   */

But it was created before there existed Python type hints. So, to define every <abbr title="the definition of how data should be formed">schema</abbr> you need to use specific utils and classes provided by Marshmallow.

/// check | Inspired **FastAPI** to

Use code to define "schemas" that provide data types and validation, automatically.

///

  }

  /**
   * A {@code CycleDetectingLockFactory.WithExplicitOrdering} provides the additional enforcement of
   * an application-specified ordering of lock acquisitions. The application defines the allowed
   * ordering with an {@code Enum} whose values each correspond to a lock type. The order in which
   * the values are declared dictates the allowed order of lock acquisition. In other words, locks

 * loading), and fewer <a
 * href="https://github.com/google/guava/issues?q=is%3Aopen+is%3Aissue+label%3Apackage%3Dcache+label%3Atype%3Ddefect">bugs</a>.
 *
 * <p>Caffeine defines its own interfaces (<a
 * href="https://www.javadoc.io/doc/com.github.ben-manes.caffeine/caffeine/latest/com.github.benmanes.caffeine/com/github/benmanes/caffeine/cache/Cache.html">{@code
 * Cache}</a>, <a

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_2016-02-06_

 *  New: WebSockets now defer some writes. This should improve performance for
    some applications.
 *  New: Override `equals()` and `hashCode()` in our new cookie class. This
    class now defines equality by value rather than by reference.
 *  New: Handle 408 responses by retrying the request. This allows servers to
    direct clients to retry rather than failing permanently.