## Recap { #recap }

With what you have seen up to now, you can set up a secure **FastAPI** application using standards like OAuth2 and JWT.

In almost any framework handling the security becomes a rather complex subject quite quickly.

### 后台任务与带 `yield` 的依赖项（技术细节） { #background-tasks-and-dependencies-with-yield-technical-details }

在 FastAPI 0.106.0 之前，`yield` 之后抛出异常是不可行的，因为带 `yield` 的依赖项中的退出代码会在响应发送之后才执行，此时[异常处理器](../tutorial/handling-errors.md#install-custom-exception-handlers)已经运行完毕。

之所以这样设计，主要是为了允许在后台任务中继续使用依赖项通过 `yield`“产出”的对象，因为退出代码会在后台任务完成之后才执行。

在 FastAPI 0.106.0 中，这一行为被修改，目的是避免在等待响应通过网络传输时一直占用资源。

/// tip | 提示

 *   <li>Extracting child URLs and adding them to the queue using {@link #storeChildUrls(Set, String, int)}
 *       or {@link #storeChildUrl(String, String, float, int)}.</li>
 *   <li>Handling exceptions that may occur during the crawling process.</li>
 * </ol>
 *
 * <p>
 * The thread also manages the active thread count using atomic operations
 * and provides methods for logging messages using {@link LogHelper}.

            // Should either throw exception or fail gracefully after wipe
            try {
                digest.sign(data, 0, data.length, request, response);
                // If no exception is thrown, accept graceful handling
                assertTrue(true, "Sign operation after wipe should either throw exception or handle gracefully");
            } catch (RuntimeException e) {

        assertNotNull(result);
        assertNotNull(thumbnailJob.sessionId);
        assertTrue(result.contains("Session Id: " + thumbnailJob.sessionId));
        // Exception handling may vary, just verify result is not null
    }

    // Test executeThumbnailGenerator with process failure
    @Test
    public void test_executeThumbnailGenerator_processFailure() {

        }

        // All threads should complete successfully
        for (boolean s : success) {
            assertTrue(s);
        }
    }

    @DisplayName("Test exception handling for invalid information levels")
    @ParameterizedTest
    @ValueSource(ints = { 0, 1, 2, 4, 5, 6, 8, 100, -2, -100, Integer.MIN_VALUE, Integer.MAX_VALUE })
    void testInvalidInformationLevels(int invalidLevel) {

#### Define a *path operation decorator* { #define-a-path-operation-decorator }

{* ../../docs_src/first_steps/tutorial001_py310.py hl[6] *}

The `@app.get("/")` tells **FastAPI** that the function right below is in charge of handling requests that go to:

* the path `/`
* using a <dfn title="an HTTP GET method"><code>get</code> operation</dfn>

/// info | `@decorator` Info

That `@something` syntax in Python is called a "decorator".

{* ../../docs_src/dependencies/tutorial008b_an_py310.py hl[18:22,31] *}

Si vous souhaitez intercepter des exceptions et créer une réponse personnalisée en fonction de cela, créez un [Gestionnaire d'exceptions personnalisé](../handling-errors.md#install-custom-exception-handlers).

## Utiliser des dépendances avec `yield` et `except` { #dependencies-with-yield-and-except }

        assertNotNull(result);
        assertSame(messages, result);
        assertTrue(messages.hasMessageOf(property));
    }

    // Test null property handling
    @Test
    public void test_addErrorsFrontHeader_nullProperty() {
        try {
            messages.addErrorsFrontHeader(null);
            fail("Should throw exception for null property");

            assertTrue((noPropagation & ACE.FLAGS_NO_PROPAGATE) != 0, "Should include no propagate flag");
        }
    }

    @Nested
    @DisplayName("Interface Edge Case Handling")
    class InterfaceEdgeCaseTests {

        @Test
        @DisplayName("Should handle null SID from interface methods")
        void shouldHandleNullSID() {
            ACE ace = mock(ACE.class);