# 使用数据类

FastAPI 基于 **Pydantic** 构建，前文已经介绍过如何使用 Pydantic 模型声明请求与响应。

但 FastAPI 还可以使用数据类（<a href="https://docs.python.org/3/library/dataclasses.html" class="external-link" target="_blank">`dataclasses`</a>）：

```Python hl_lines="1  7-12  19-20"
{!../../docs_src/dataclasses/tutorial001.py!}
```

/* jcifs smb client library in Java
 * Copyright (C) 2006  "Michael B. Allen" <jcifs at samba dot org>
 *                     "Eric Glass" <jcifs at samba dot org>
 * 
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * 

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@IgnoreJRERequirement // We opt into library desugaring for our tests.
public class MapComputeIfAbsentTester<K, V> extends AbstractMapTester<K, V> {

  @MapFeature.Require(SUPPORTS_PUT)
  public void testComputeIfAbsent_supportedAbsent() {
    assertEquals(

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@IgnoreJRERequirement // We opt into library desugaring for our tests.
public class MapReplaceEntryTester<K, V> extends AbstractMapTester<K, V> {

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)

	istiolog.Error("error log")
	istiolog.WithLabels("key", 2).Infof("with labels")
	// This will error because stdout cannot sync, but the UDS part should sync
	// Ideally we would fail if the UDS part fails but the error library makes it kind of tricky
	_ = istiolog.Sync()

	// Restore os stdout.
	os.Stdout = stdout
	assert.NoError(t, istiolog.Configure(loggingOptions))

	assert.NoError(t, w.Close())
	out, err := io.ReadAll(r)

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@IgnoreJRERequirement // We opt into library desugaring for our tests.
public class MapGetOrDefaultTester<K, V> extends AbstractMapTester<K, V> {
  @CollectionSize.Require(absent = ZERO)
  public void testGetOrDefault_present() {
    assertEquals(

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@IgnoreJRERequirement // We opt into library desugaring for our tests.
public class CollectionRemoveIfTester<E> extends AbstractCollectionTester<E> {
  @CollectionFeature.Require(SUPPORTS_ITERATOR_REMOVE)
  public void testRemoveIf_alwaysFalse() {

// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@IgnoreJRERequirement // We opt into library desugaring for our tests.
public class MapReplaceTester<K, V> extends AbstractMapTester<K, V> {

  @MapFeature.Require(SUPPORTS_PUT)
  @CollectionSize.Require(absent = ZERO)
  public void testReplace_supportedPresent() {

```Python hl_lines="10  12-13"
{!../../docs_src/middleware/tutorial001.py!}
```

/// tip

Here we use <a href="https://docs.python.org/3/library/time.html#time.perf_counter" class="external-link" target="_blank">`time.perf_counter()`</a> instead of `time.time()` because it can be more precise for these use cases. 🤓

///

## Other middlewares

Starlette (and **FastAPI**) are based on <a href="https://anyio.readthedocs.io/en/stable/" class="external-link" target="_blank">AnyIO</a>, which makes it compatible with both Python's standard library <a href="https://docs.python.org/3/library/asyncio-task.html" class="external-link" target="_blank">asyncio</a> and <a href="https://trio.readthedocs.io/en/stable/" class="external-link" target="_blank">Trio</a>.