But FastAPI also supports using <a href="https://docs.python.org/3/library/dataclasses.html" class="external-link" target="_blank">`dataclasses`</a> the same way:

{* ../../docs_src/dataclasses/tutorial001.py hl[1,7:12,19:20] *}

比如，如果您需要将其存储在数据库中。

对于这种要求， **FastAPI**提供了`jsonable_encoder()`函数。

## 使用`jsonable_encoder`

让我们假设你有一个数据库名为`fake_db`，它只能接收与JSON兼容的数据。

例如，它不接收`datetime`这类的对象，因为这些对象与JSON不兼容。

因此，`datetime`对象必须将转换为包含<a href="https://en.wikipedia.org/wiki/ISO_8601" class="external-link" target="_blank">ISO格式化</a>的`str`类型对象。

同样，这个数据库也不会接收Pydantic模型（带有属性的对象），而只接收`dict`。

对此你可以使用`jsonable_encoder`。

它接收一个对象，比如Pydantic模型，并会返回一个JSON兼容的版本：

    Don't call it directly, FastAPI will call it for you.

    Read more about it in the
    [FastAPI docs for Security](https://fastapi.tiangolo.com/tutorial/security/) and
    in the
    [FastAPI docs for OAuth2 scopes](https://fastapi.tiangolo.com/advanced/security/oauth2-scopes/).

    **Example**

    ```python
    from typing import Annotated

    client_id: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    client_secret: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    """

    def __init__(
        self,
        grant_type: Annotated[
            str,

# > target platform.
# See also https://docs.bazel.build/versions/master/guide.html#build-configurations-and-cross-compilation
build --distinct_host_configuration=false

# Store performance profiling log in the mounted artifact directory.
# The profile can be viewed by visiting chrome://tracing in a Chrome browser.
# See https://docs.bazel.build/versions/main/skylark/performance.html#performance-profiling

import okhttp3.internal.hasIntersection
import okhttp3.internal.indexOf
import okhttp3.internal.intersect

/**
 * Specifies configuration for the socket connection that HTTP traffic travels through. For `https:`
 * URLs, this includes the TLS version and cipher suites to use when negotiating a secure
 * connection.
 *
 * The TLS versions configured in a connection spec are only be used if they are also enabled in the

Se você quiser ler mais sobre essas codificações e campos de formulário, vá para o <a href="https://developer.mozilla.org/pt-BR/docs/Web/HTTP/Methods/POST" class="external-link" target="_blank"><abbr title="Mozilla Developer Network">MDN</abbr> web docs para <code>POST</code></a>.

///

/// warning | "Aviso"

✍ 🛠️ 👆 ⚙️ 👨‍🎨 `@app.middleware("http")` 🔛 🔝 🔢.

🛠️ 🔢 📨:

*  `request`.
* 🔢 `call_next` 👈 🔜 📨 `request` 🔢.
    * 👉 🔢 🔜 🚶‍♀️ `request` 🔗 *➡ 🛠️*.
    * ⤴️ ⚫️ 📨 `response` 🏗 🔗 *➡ 🛠️*.
* 👆 💪 ⤴️ 🔀 🌅 `response` ⏭ 🛬 ⚫️.

```Python hl_lines="8-9  11  14"
{!../../docs_src/middleware/tutorial001.py!}
```

/// tip

 *
 * All callback methods (will) follow beforeXXX/afterXXX naming pattern to
 * indicate at what lifecycle point it is being called.
 *
 * @see <a href="https://maven.apache.org/examples/maven-3-lifecycle-extensions.html">example</a>
 * @see <a href="https://issues.apache.org/jira/browse/MNG-4224">MNG-4224</a>
 * @since 3.0-alpha-3
 */
public abstract class AbstractMavenLifecycleParticipant {

    /**

    val request = Request.Builder().url("https://mozilla.org/robots.txt").build()

    client.newCall(request).execute().use {
      assertThat(it.protocol).isEqualTo(Protocol.HTTP_2)
      assertThat(it.handshake!!.tlsVersion).isEqualTo(TlsVersion.TLS_1_3)
    }
  }

  @Test
  @Disabled
  fun testGoogle() {
    assumeNetwork()

    val request = Request.Builder().url("https://google.com/robots.txt").build()