* 数据转换
* 数据校验
* 自动生成文档

## 特殊的类型和校验

除了普通的单一值类型（如 `str`、`int`、`float` 等）外，你还可以使用从 `str` 继承的更复杂的单一值类型。

要了解所有的可用选项，请查看关于 <a href="https://docs.pydantic.dev/latest/concepts/types/" class="external-link" target="_blank">来自 Pydantic 的外部类型</a> 的文档。你将在下一章节中看到一些示例。

例如，在 `Image` 模型中我们有一个 `url` 字段，我们可以把它声明为 Pydantic 的 `HttpUrl`，而不是 `str`：

//// tab | Python 3.10+

```Python hl_lines="2  8"

      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions

 * capabilities to the default HTTP handler. This acts as a wrapper,
 * handling authentication and passing control to the underlying
 * stream handler.
 * 
 * @deprecated {@link NtlmHttpURLConnection} is broken by design.
 */
@Deprecated
public class Handler extends URLStreamHandler {

    private static final Logger log = LoggerFactory.getLogger(Handler.class);

    /**

import org.apache.maven.model.v4.MavenStaxReader;
import org.codehaus.plexus.util.xml.XmlStreamWriter;

/**
 * Handles deserialization of a model from some kind of textual format like XML.
 *
 * @deprecated use {@link XmlStreamWriter} instead
 */
@Named
@Singleton
@Deprecated(since = "4.0.0")
public class DefaultModelReader implements ModelReader {
    private final ModelSourceTransformer transformer;

    @Inject

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import org.junit.Ignore;

/**
 * Tests for {@link Multimap#asMap}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")

import com.google.common.collect.testing.features.MapFeature;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import org.junit.Ignore;

/**
 * Tests for {@link Multimap#remove(Object, Object)}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore // Affects only Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.

import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link FakeTicker}.
 *
 * @author Jige Yu
 */
@GwtCompatible(emulated = true)
// We also want to test the TimeUnit overload (especially under GWT, where it's the only option).
@SuppressWarnings("SetAutoIncrementStep_Nanos")

import com.google.common.testing.NullPointerTester;
import java.util.Map.Entry;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tests for {@link ImmutableMultimap}.
 *
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
public class ImmutableMultimapTest extends TestCase {

  @SuppressWarnings("JUnitIncompatibleType")

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;

import junit.framework.TestCase;

/**
 * Tests for {@link LinearTransformation}.
 *
 * @author Pete Gillin
 */
public class LinearTransformationTest extends TestCase {

  private static final double ALLOWED_ERROR = 1e-10;

  public void testMappingAnd_regular() {

import com.google.common.testing.NullPointerTester;
import com.google.common.testing.SerializableTester;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link Equivalence}.
 *
 * @author Jige Yu
 */
@ElementTypesAreNonnullByDefault
@GwtCompatible(emulated = true)
public class EquivalenceTest extends TestCase {
  public void testPairwiseEquivalent() {