#### 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);

但如果你需要，它就在這裡。🤓

///

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

如果你想攔截例外並據此回傳自訂回應，請建立一個[自訂例外處理器](../handling-errors.md#install-custom-exception-handlers)。

## 含 `yield` 與 `except` 的相依 { #dependencies-with-yield-and-except }

如果你在含 `yield` 的相依中用 `except` 攔截了例外，且沒有再次拋出它（或拋出新的例外），FastAPI 將無法察覺有例外發生，就像在一般的 Python 中一樣：

        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) {

            if (e.getCause().getMessage() != null) {
                assertTrue(e.getCause().getMessage().contains("Process start failed"));
            }
        }
    }

    // Test execute with exception handling
    @Test
    public void test_execute_withException() {
        pythonJob.filename("test.py");

        testProcessHelper.throwException = new RuntimeException("Unexpected error");

///

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

If you want to catch exceptions and create a custom response based on that, create a [Custom Exception Handler](../handling-errors.md#install-custom-exception-handlers).

## Dependencies with `yield` and `except` { #dependencies-with-yield-and-except }

 * This class contains various helper methods for formatting, parsing, and manipulating data
 * in Fess web templates, including date formatting, localization, file operations, and
 * query parameter handling.
 *
 * @since 1.0
 */
public class FessFunctions {
    /** Logger instance for this class */
    private static final Logger logger = LogManager.getLogger(FessFunctions.class);