И, вероятно, он будет заметно отличаться от одного приложения к другому.

Это могут быть буквально одна-две строки кода, например:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"
httpx.post(callback_url, json={"description": "Invoice paid", "paid": True})
```

**FastAPI**将保留来自 `responses` 的附加信息，并将其与模型中的JSON Schema结合起来。

例如，您可以使用状态码 `404` 声明响应，该响应使用`Pydantic`模型并具有自定义的` description` 。

以及一个状态码为 `200` 的响应，它使用您的 `response_model` ，但包含自定义的 `example` ：

{* ../../docs_src/additional_responses/tutorial003.py hl[20:31] *}

所有这些都将被合并并包含在您的OpenAPI中，并在API文档中显示：

## 联合预定义响应和自定义响应

您可能希望有一些应用于许多路径操作的预定义响应，但是你想将不同的路径和自定义的相应组合在一块。

	} `xml:"SystemRecommendations"`
}

// This optional functionality allows vendors to report space information to Veeam products, and Veeam will make placement
// decisions based on this information. For example, Veeam Backup & Replication has a Scale-out-Backup-Repository feature where
// multiple buckets can be used together. The placement logic for additional backup files is based on available space. Other values

 * <p>Some uses of this class include
 *
 * <ul>
 *   <li>As a method return type, as an alternative to returning {@code null} to indicate that no
 *       value was available
 *   <li>To distinguish between "unknown" (for example, not present in a map) and "known to have no
 *       value" (present in the map, with value {@code Optional.absent()})
 *   <li>To wrap nullable references for storage in a collection that does not support {@code null}

    return result;
  }

  public abstract static class TestDoubleListGenerator implements TestListGenerator<Double> {
    @Override
    public SampleElements<Double> samples() {
      return new SampleDoubles();
    }

    @Override
    public List<Double> create(Object... elements) {
      Double[] array = new Double[elements.length];
      int i = 0;

In some cases, it's even possible to have both Pydantic v1 and v2 models in the same **path operation** in your FastAPI app:

{* ../../docs_src/pydantic_v1_in_v2/tutorial003_an_py310.py hl[2:3,6,12,21:22] *}

In this example above, the input model is a Pydantic v1 model, and the output model (defined in `response_model=ItemV2`) is a Pydantic v2 model.

### Pydantic v1 parameters { #pydantic-v1-parameters }

 * more ACEs are evaluated until all desired access bits (combined)
 * are "allowed". If all of the desired access bits are not "allowed"
 * the then same process is repeated for inherited ACEs.
 * <p>
 * For example, if user <code>WNET\alice</code> tries to open a file
 * with desired access bits <code>0x00000003</code> (<code>FILE_READ_DATA |
 * FILE_WRITE_DATA</code>) and the target file has the following security
 * descriptor ACEs:
 *

Bevor wir tiefer in das **Dependency Injection** System eintauchen, lassen Sie uns das vorherige Beispiel verbessern.

## Ein `dict` aus dem vorherigen Beispiel { #a-dict-from-the-previous-example }

Im vorherigen Beispiel haben wir ein <abbr title="Dictionary – Zuordnungstabelle: In anderen Sprachen auch Hash, Map, Objekt, Assoziatives Array genannt">`dict`</abbr> von unserer Abhängigkeit („Dependable“) zurückgegeben:

            Maps.asMap(graph.adjacentNodes(node), successorNodeToValueFn));
  }

  /**
   * A builder for creating {@link ImmutableValueGraph} instances, especially {@code static final}
   * graphs. Example:
   *
   * {@snippet :
   * static final ImmutableValueGraph<City, Distance> CITY_ROAD_DISTANCE_GRAPH =
   *     ValueGraphBuilder.undirected()
   *         .<City, Distance>immutable()

<img src="/img/tutorial/security/image12.png">

## Check the username { #check-the-username }

Here's a more complete example.

Use a dependency to check if the username and password are correct.