添加回调前，首先看下常规 API 应用是什么样子。

常规 API 应用包含接收 `Invoice` 请求体的*路径操作*，还有包含回调 URL 的查询参数 `callback_url`。

这部分代码很常规，您对绝大多数代码应该都比较熟悉了：

```Python hl_lines="10-14  37-54"
{!../../docs_src/openapi_callbacks/tutorial001.py!}
```

/// tip | "提示"

`callback_url` 查询参数使用 Pydantic 的 <a href="https://pydantic-docs.helpmanual.io/usage/types/#urls" class="external-link" target="_blank">URL</a> 类型。

///

    {
      "type": "int_parsing",
      "loc": [
        "path",
        "item_id"
      ],
      "msg": "Input should be a valid integer, unable to parse string as an integer",
      "input": "foo",
      "url": "https://errors.pydantic.dev/2.1/v/int_parsing"
    }
  ]
}
```

Çünkü burada `item_id` yol parametresi `int` tipinde bir değer beklerken `"foo"` yani `string` tipinde bir değer almıştı.

import jetbrains.buildServer.configs.kotlin.ui.add
import java.util.Locale

const val pluginPortalUrlOverride = "-Dorg.gradle.internal.plugins.portal.url.override=%gradle.plugins.portal.url%"

fun BuildSteps.customGradle(init: GradleBuildStep.() -> Unit, custom: GradleBuildStep.() -> Unit): GradleBuildStep =
    GradleBuildStep(init)
        .apply(custom)
        .also {
            step(it)

import java.io.IOException
import okhttp3.OkHttpClient
import okhttp3.Request

class AccessHeaders {
  private val client = OkHttpClient()

  fun run() {
    val request =
      Request.Builder()
        .url("https://api.github.com/repos/square/okhttp/issues")
        .header("User-Agent", "OkHttp Headers.java")
        .addHeader("Accept", "application/json; q=0.5")
        .addHeader("Accept", "application/vnd.github.v3+json")

🔜, 🏃 `uvicorn` ⏮️ 👑 📱, 🚥 👆 📁 `main.py`, ⚫️ 🔜:

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

&amp; 📂 🩺 <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

👆 🔜 👀 🏧 🛠️ 🩺 👑 📱, 🔌 🕴 🚮 👍 _➡ 🛠️_:

当你使用 `Query` 显式地定义查询参数时，你还可以声明它去接收一组值，或换句话来说，接收多个值。

例如，要声明一个可在 URL 中出现多次的查询参数 `q`，你可以这样写：

```Python hl_lines="9"
{!../../docs_src/query_params_str_validations/tutorial011.py!}
```

然后，输入如下网址：

```
http://localhost:8000/items/?q=foo&q=bar
```

你会在*路径操作函数*的*函数参数* `q` 中以一个 Python `list` 的形式接收到*查询参数* `q` 的多个值（`foo` 和 `bar`）。

因此，该 URL 的响应将会是：

```JSON
{
  "q": [
    "foo",
    "bar"

<div class="termy">

```console
$ uvicorn main:app --reload

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
<span style="color: green;">INFO</span>:     Started reloader process [28720]
<span style="color: green;">INFO</span>:     Started server process [28722]

/**
 * ArtifactRepositoryLayout2
 */
public interface ArtifactRepositoryLayout2 extends ArtifactRepositoryLayout {

    ArtifactRepository newMavenArtifactRepository(
            String id, String url, ArtifactRepositoryPolicy snapshots, ArtifactRepositoryPolicy releases);

/**
 * @author shinsuke
 *
 */
public interface UrlQueueService<QUEUE extends UrlQueue<?>> {

    void updateSessionId(String oldSessionId, String newSessionId);

    void add(String sessionId, String url);

    void insert(QUEUE urlQueue);

    void delete(String sessionId);

    void deleteAll();

    void offerAll(String sessionId, List<QUEUE> newUrlQueueList);

    QUEUE poll(String sessionId);

		internalLogIf(ctx, err)
	}

	return
}

// VerifyBinary - asks remote peers to verify the checksum
func (sys *NotificationSys) VerifyBinary(ctx context.Context, u *url.URL, sha256Sum []byte, releaseInfo string, bin []byte) []NotificationPeerErr {
	// FIXME: network calls made in this manner such as one goroutine per node,
	// can easily eat into the internode bandwidth. This function would be mostly