---

## Installer FastAPI

La première étape consiste à installer FastAPI.

Pour le tutoriel, vous voudrez peut-être l'installer avec toutes les dépendances et fonctionnalités optionnelles :

<div class="termy">

```console
$ pip install fastapi[all]

---> 100%
```

</div>

* L'utilisation de **contraintes de validation** comme `maximum_length` ou `regex`.
* Un **<abbr title="aussi connu sous le nom de composants, ressources, fournisseurs, services, injectables">système d'injection de dépendance </abbr>** très puissant et facile à utiliser .

     */
    @Nonnull
    String asString();

    /**
     * Obtain a Stream containing this node and all its descendants.
     *
     * @return a stream containing this node and its descendants
     */
    @Nonnull
    default Stream<Node> stream() {
        return Stream.concat(Stream.of(this), getChildren().stream().flatMap(Node::stream));
    }

     */
    @Nonnull
    Optional<Boolean> alsoMake();

    /**
     * Indicates whether Maven should also build the specified projects' dependents.
     *
     * @return an {@link Optional} containing true if dependents should also be built, false if not, or empty if not specified
     */
    @Nonnull
    Optional<Boolean> alsoMakeDependents();

    /**

    /**
     * Expands a version range to a list of matching versions, in ascending order.
     * For example, resolves "[3.8,4.0)" to "3.8", "3.8.1", "3.8.2".
     * The returned list of versions is only dependent on the configured repositories and their contents.
     * The supplied request may also refer to a single concrete version rather than a version range.

Ele sempre terá os escopos de segurança declarados nas dependências atuais de `Security` e todos os dependentes para **aquela** *operação de rota* **específica** e **aquela** árvore de dependência **específica**.

Disons que vous avez seulement un paramètre `item` dans le body, correspondant à un modèle Pydantic `Item`.

Par défaut, **FastAPI** attendra sa déclaration directement dans le body.

///

### Import `Depends` { #import-depends }

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[3] *}

### Declare the dependency, in the "dependant" { #declare-the-dependency-in-the-dependant }

The same way you use `Body`, `Query`, etc. with your *path operation function* parameters, use `Depends` with a new parameter:

{* ../../docs_src/dependencies/tutorial001_an_py310.py hl[13,18] *}

     */
    private static List<Path> paths() {
        return List.of(Path.of("src", "foo.java"), Path.of("src", "bar.java"));
    }

    /**
     * Converts paths from Unix style to platform-dependent style.
     *
     * @param expected the option value expected by the test
     * @return the expected value with separators of the host
     */
    private static String toPlatformSpecific(String expected) {

 *   <dt>{@link ListMultimap}
 *   <dd>An extension of {@link Multimap} which permits duplicate entries, supports random access of
 *       values for a particular key, and has <i>partially order-dependent equality</i> as defined
 *       by {@link ListMultimap#equals(Object)}. {@code ListMultimap} takes its name from the fact
 *       that the {@linkplain ListMultimap#get collection of values} associated with a given key