注意預設值仍然是 `None`，所以這個參數仍是可選。

不過，現在在 `Annotated` 裡有 `Query(max_length=50)`，我們就告訴 FastAPI 要對這個值做「額外驗證」，最多 50 個字元即可。😎

/// tip | 提示

這裡用的是 `Query()`，因為這是「查詢參數」。稍後你會看到 `Path()`、`Body()`、`Header()`、`Cookie()` 等，它們也接受與 `Query()` 相同的參數。

///

FastAPI 現在會：

- 驗證資料，確保長度最多 50 個字元
- 當資料不合法時，回給用戶端清楚的錯誤
- 在 OpenAPI 的路徑操作中文件化該參數（因此會出現在自動文件 UI）

**Repository:** [https://github.com/elastic/elasticsearch](https://github.com/elastic/elasticsearch)

JDK 16 is required to build Elasticsearch. You must have a JDK 16 installation
with the environment variable `JAVA_HOME` referencing the path to Java home for
your JDK 16 installation. By default, tests use the same runtime as `JAVA_HOME`.
However, since Elasticsearch supports JDK 11, the build supports compiling with

   * C} will be excluded from automated serialization test performed by this method.
   */
  @Test
  public void testSerializable() throws Exception {
    // TODO: when we use @BeforeClass, we can pay the cost of class path scanning only once.
    for (Class<?> classToTest :
        findClassesToTest(loadClassesInPackage(), SERIALIZABLE_TEST_METHOD_NAMES)) {
      if (Serializable.class.isAssignableFrom(classToTest)) {
        try {

And still, you would probably not want the application to stay dead because there was an error in one place, you probably want it to **continue running** at least for the *path operations* that are not broken.

### Restart After Crash { #restart-after-crash }

// Create adds a file to the zip file using the provided name.
// It returns a [Writer] to which the file contents should be written.
// The file contents will be compressed using the [Deflate] method.
// The name must be a relative path: it must not start with a drive
// letter (e.g. C:) or leading slash, and only forward slashes are
// allowed. To create a directory instead of a file, add a trailing

     * provided in the {@code paramMap}. If the {@code URL_EXCLUDE_PATTERN} key exists in
     * the parameter map, its value is used as a regular expression pattern to match against
     * the given URL. If the URL matches the exclusion pattern, the method returns {@code false},
     * indicating that the URL should not be crawled. Otherwise, it returns {@code true}.
     *

    }

    /*
     * These methods "should" call checkNotNull. However, I'm wary of accidentally introducing
     * anything that might slow down execution on such a hot path. Given that the methods are only
     * package-private, I feel OK with just not testing them for NPE.
     *
     * Note that testing casValue is particularly dangerous because it uses Unsafe under some

      return false;
    }
    for (int i = 0; i < length(); i++) {
      if (!areEqual(this.get(i), that.get(i))) {
        return false;
      }
    }
    return true;
  }

  // Match the behavior of Double.equals()
  private static boolean areEqual(double a, double b) {
    return Double.doubleToLongBits(a) == Double.doubleToLongBits(b);
  }

/// tip | Astuce

Ici nous utilisons `Query()` parce qu’il s’agit d’un **paramètre de requête**. Plus tard nous verrons d’autres comme `Path()`, `Body()`, `Header()` et `Cookie()`, qui acceptent également les mêmes arguments que `Query()`.

///

FastAPI va maintenant :

- **Valider** les données en s’assurant que la longueur maximale est de 50 caractères

    assertTrue(range.containsAll(asList(3, 3, 4, 5)));
    assertFalse(range.containsAll(asList(3, 3, 4, 5, 6)));

    // We happen to know that natural-order sorted sets use a different code
    // path, so we test that separately
    assertTrue(range.containsAll(ImmutableSortedSet.of(3, 3, 4, 5)));
    assertTrue(range.containsAll(ImmutableSortedSet.of(3)));
    assertTrue(range.containsAll(ImmutableSortedSet.<Integer>of()));