In this section you will see how to manage authentication and authorization with the same OAuth2 with scopes in your **FastAPI** application.

/// warning

This is a more or less advanced section. If you are just starting, you can skip it.

You don't necessarily need OAuth2 scopes, and you can handle authentication and authorization however you want.

   * iterable}. The iterator's {@code hasNext()} method returns {@code true} until {@code iterable}
   * is empty.
   *
   * <p><b>Warning:</b> Typical uses of the resulting iterator may produce an infinite loop. You
   * should use an explicit {@code break} or be certain that you will eventually remove all the
   * elements.
   */

        Result<? extends ProjectDependencyGraph> graphResult = graphBuilder.build(session);
        for (ModelProblem problem : graphResult.getProblems()) {
            if (problem.getSeverity() == ModelProblem.Severity.WARNING) {
                logger.warn(problem.getMessage());
            } else {
                logger.error(problem.getMessage());
            }
        }

        if (!graphResult.hasErrors()) {

   * termination, or other problems, {@code to} may not be a complete copy of {@code from}. If you
   * need to guard against those conditions, you should employ other file-level synchronization.
   *
   * <p><b>Warning:</b> If {@code to} represents an existing file, that file will be overwritten
   * with the contents of {@code from}. If {@code to} and {@code from} refer to the <i>same</i>
   * file, the contents of that file will be deleted.

      return constructor.newInstance();
    } catch (InstantiationException | IllegalAccessException impossible) {
      throw new AssertionError(impossible);
    } catch (InvocationTargetException e) {
      logger.log(Level.WARNING, "Exception while invoking default constructor.", e.getCause());
      return arbitraryConstantInstanceOrNull(type);
    }
  }

  private static <T> @Nullable T arbitraryConstantInstanceOrNull(Class<T> type) {

<img src="/img/tutorial/behind-a-proxy/image02.png">

一切正常。 ✔️

这是因为 FastAPI 在 OpenAPI 里使用 `root_path` 提供的 URL 创建默认 `server`。

## 附加的服务器

/// warning | 警告

此用例较难，可以跳过。

///

默认情况下，**FastAPI** 使用 `root_path` 的链接在 OpenAPI 概图中创建 `server`。

但也可以使用其它备选 `servers`，例如，需要同一个 API 文档与 staging 和生产环境交互。

### Использование менеджеров контекста в зависимостях с `yield` { #using-context-managers-in-dependencies-with-yield }

/// warning | Внимание

Это, более или менее, «продвинутая» идея.

Если вы только начинаете работать с **FastAPI**, то лучше пока пропустить этот пункт.

///

       */
      try (URLClassLoader finalizerLoader = newLoader(getBaseUrl())) {
        return finalizerLoader.loadClass(FINALIZER_CLASS_NAME);
      } catch (Exception e) {
        logger.log(Level.WARNING, LOADING_ERROR, e);
        return null;
      }
    }

    /** Gets URL for base of path containing Finalizer.class. */
    URL getBaseUrl() throws IOException {

common:ios --noenable_platform_specific_config

# Suppress all C++ compiler warnings, otherwise build logs become 10s of MBs.
common:android --copt=-w
common:ios --copt=-w
common:linux --host_copt=-w
common:macos --copt=-w
common:windows --copt=/W0
common:windows --host_copt=/W0

# Suppress most C++ compiler warnings to reduce log size but allow
# for specific warnings to still be present.
common:linux --copt="-Wno-all"

Nesta seção, você verá como gerenciar a autenticação e autorização com os mesmos escopos do OAuth2 em sua aplicação **FastAPI**.

/// warning | Atenção

Isso é uma seção mais ou menos avançada. Se você está apenas começando, você pode pular.