"timestamp": "2023-01-01T12:00:00",
            "description": "An optional description",
        },
    )
    assert response.status_code == 200
    assert "123" in fake_db
    assert fake_db["123"] == {
        "title": "Foo",
        "timestamp": "2023-01-01T12:00:00",
        "description": "An optional description",
    }


def test_put_invalid_data(client: TestClient, mod: ModuleType):

    }

    private static void trimValues(MavenProperties configProps) {
        configProps.replaceAll((k, v) -> v.trim());
    }

    private static String nextLocation(StringTokenizer st) {
        boolean optional = false;
        String retVal = null;

        if (st.countTokens() > 0) {
            String tokenList = "?\",";
            StringBuilder tokBuf = new StringBuilder(10);
            String tok;

def get_current_user(oauth_header: Optional[str] = Security(reusable_oauth2)):
    if oauth_header is None:
        return None
    user = User(username=oauth_header)
    return user


@app.post("/login")
def login(form_data: OAuth2PasswordRequestFormStrict = Depends()):
    return form_data


@app.get("/users/me")
def read_users_me(current_user: Optional[User] = Depends(get_current_user)):

    }

    @Override
    public Path getRootDirectory() {
        return project.getRootDirectory();
    }

    @Override
    public Optional<Project> getParent() {
        MavenProject parent = project.getParent();
        return Optional.ofNullable(session.getProject(parent));
    }

    @Override
    @Nonnull
    public List<Profile> getDeclaredProfiles() {

     */
    @Size(max = 10000)
    @Required
    public String rt;

    /**
     * Hash value for security or validation purposes.
     * This field is optional and used for request verification.
     */
    public String hash;

    /**
     * Query identifier associated with the search that led to this document access.

    return pickInstance(Currency.getAvailableCurrencies(), Currency.getInstance(Locale.US));
  }

  @Empty
  <T> Optional<T> generateJavaOptional() {
    return Optional.empty();
  }

  @Generates
  <T> Optional<T> generateJavaOptional(T value) {
    return Optional.of(value);
  }

  @Generates
  OptionalInt generateOptionalInt() {
    return OptionalInt.of(generateInt());
  }

本例中，查询参数 `q` 是可选的，默认值为 `None`。

/// check | 检查

注意，**FastAPI** 可以识别出 `item_id` 是路径参数，`q` 不是路径参数，而是查询参数。

///

/// note | 笔记

因为默认值为 `= None`，FastAPI 把 `q` 识别为可选参数。

FastAPI 不使用 `Optional[str]` 中的 `Optional`（只使用 `str`），但 `Optional[str]` 可以帮助编辑器发现代码中的错误。

///

## 查询参数类型转换

参数还可以声明为 `bool` 类型，FastAPI 会自动转换参数类型：


{* ../../docs_src/query_params/tutorial003_py310.py hl[7] *}

本例中，访问：

```

   * implementations.
   */
  SUPPORTS_SET;

  /**
   * A set containing none of the optional features of the {@link Iterator} or {@link ListIterator}
   * interfaces.
   */
  public static final Set<IteratorFeature> UNMODIFIABLE = emptySet();

  /**
   * A set containing all of the optional features of the {@link Iterator} and {@link ListIterator}
   * interfaces.
   */

                        .nonRecursive()
                        .expectResult(MODULE_C),
                scenario("Selected optional project")
                        .activeOptionalProjects(MODULE_B)
                        .expectResult(MODULE_B),
                scenario("Selected missing optional project")
                        .activeOptionalProjects("non-existing-module")
                        .expectResult(

     * @see org.apache.maven.api.services.ArtifactManager#getPath(Artifact)
     */
    @Nonnull
    default Optional<ProducedArtifact> getMainArtifact() {
        List<ProducedArtifact> artifacts = getArtifacts();
        return artifacts.size() == 2 ? Optional.of(artifacts.get(1)) : Optional.empty();
    }

    /**