Aber in realen Fällen würden Sie bei der Implementierung von Sicherheit mehr Vorteile durch die Verwendung der integrierten [Sicherheits-Werkzeuge (siehe nächstes Kapitel)](../security/index.md){.internal-link target=_blank} erzielen.

///

## Abhängigkeitsfehler und -Rückgabewerte

Sie können dieselben Abhängigkeits-*Funktionen* verwenden, die Sie normalerweise verwenden.

### Abhängigkeitsanforderungen

## Details zum `Request`-Objekt

Da **FastAPI** unter der Haube eigentlich **Starlette** ist, mit einer Ebene von mehreren Tools darüber, können Sie Starlette's <a href="https://www.starlette.io/requests/" class="external-link" target="_blank">`Request`</a>-Objekt direkt verwenden, wenn Sie es benötigen.

# 事件：启动 - 关闭

**FastAPI** 支持定义在应用启动前，或应用关闭后执行的事件处理器（函数）。

事件函数既可以声明为异步函数（`async def`），也可以声明为普通函数（`def`）。

/// warning | "警告"

**FastAPI** 只执行主应用中的事件处理器，不执行[子应用 - 挂载](sub-applications.md){.internal-link target=_blank}中的事件处理器。

///

## `startup` 事件

使用 `startup` 事件声明 `app` 启动前运行的函数：

```Python hl_lines="8"
{!../../docs_src/events/tutorial001.py!}
```

本例中，`startup` 事件处理器函数为项目数据库（只是**字典**）提供了一些初始值。

package com.google.common.base;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import com.google.common.collect.Iterables;

/**
 * Microbenchmark for {@link Splitter#on} with char vs String with length == 1.
 *
 * @author Paul Lindner
 */
public class SplitterBenchmark {
  // overall size of string
  @Param({"1", "10", "100", "1000"})
  int length;

import com.google.common.testing.SerializableTester;
import java.util.Set;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests multiset-specific serialization. Can't be invoked directly;
 * please see {@link MultisetTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible // but no-op
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

    private static long lastModified = 1L;
    private static int alt;
    private static LogStream log = LogStream.getInstance();

    /**
     * This is really just for {@link jcifs.smb1.UniAddress}. It does
     * not throw an {@link java.net.UnknownHostException} because this
     * is queried frequently and exceptions would be rather costly to
     * throw on a regular basis here.
     */

Mas em situações reais, como implementações de segurança, você pode obter mais vantagens em usar as [Ferramentas de segurança integradas (o próximo capítulo)](../security/index.md){.internal-link target=_blank}.

///

## Erros das dependências e valores de retorno

Você pode utilizar as mesmas *funções* de dependências que você usaria normalmente.

### Requisitos de Dependências

import com.google.common.annotations.GwtCompatible;
import java.util.concurrent.Future;
import javax.annotation.CheckForNull;

/**
 * Classes and futures used in {@link FuturesGetCheckedTest} and {@link FuturesGetUncheckedTest}.
 */
@GwtCompatible
final class FuturesGetCheckedInputs {
  static final Exception CHECKED_EXCEPTION = new Exception("mymessage");

 *
 * Takes the following as input:
 * <ul>
 * <li>A source docbook XML file.</li>
 * <li>Meta-info about the canonical documentation for each class referenced in the document, as produced by {@link gradlebuild.docs.dsl.docbook.AssembleDslDocTask}.</li>
 * </ul>
 *
 */
@CacheableTask
abstract class UserGuideTransformTask extends DefaultTask {

    @PathSensitive(PathSensitivity.NONE)
    @InputFile

///

/// info

你还可以使用：

* `response_model_exclude_defaults=True`
* `response_model_exclude_none=True`

参考 <a href="https://docs.pydantic.dev/latest/concepts/serialization/#modeldict" class="external-link" target="_blank">Pydantic 文档</a> 中对 `exclude_defaults` 和 `exclude_none` 的描述。