///

### Criar um `APIRouter` para o callback

Primeiramente crie um novo `APIRouter` que conterá um ou mais callbacks.

```Python hl_lines="3  25"
{!../../docs_src/openapi_callbacks/tutorial001.py!}
```

### Crie a *operação de rota* do callback

Para criar a *operação de rota* do callback, use o mesmo `APIRouter` que você criou acima.

👉 ☝ 👆 ✔️ *⏲ ➡ 🛠️(Ⓜ)* 💪 (1️⃣(Ⓜ) 👈 *🔢 👩‍💻* 🔜 🛠️ *🔢 🛠️*) ⏲ 📻 👆 ✍ 🔛.

🔜 ⚙️ 🔢 `callbacks` *👆 🛠️ ➡ 🛠️ 👨‍🎨* 🚶‍♀️ 🔢 `.routes` (👈 🤙 `list` 🛣/*➡ 🛠️*) ⚪️➡️ 👈 ⏲ 📻:

```Python hl_lines="35"
{!../../docs_src/openapi_callbacks/tutorial001.py!}
```

/// tip

👀 👈 👆 🚫 🚶‍♀️ 📻 ⚫️ (`invoices_callback_router`) `callback=`, ✋️ 🔢 `.routes`, `invoices_callback_router.routes`.

///

### ✅ 🩺

	createCallback.Clauses = config.CreateClauses

	queryCallback := db.Callback().Query()
	queryCallback.Register("gorm:query", Query)
	queryCallback.Register("gorm:preload", Preload)
	queryCallback.Register("gorm:after_query", AfterQuery)
	queryCallback.Clauses = config.QueryClauses

	deleteCallback := db.Callback().Delete()
	deleteCallback.Match(enableTransaction).Register("gorm:begin_transaction", BeginTransaction)

///

### 添加回调路由

至此，在上文创建的回调路由里就包含了*回调路径操作*（外部开发者要在外部 API 中实现）。

现在使用 API *路径操作装饰器*的参数 `callbacks`，从回调路由传递属性 `.routes`（实际上只是路由/路径操作的**列表**）：

```Python hl_lines="36"
{!../../docs_src/openapi_callbacks/tutorial001.py!}
```

/// tip | "提示"

注意，不能把路由本身（`invoices_callback_router`）传递给 `callback=`，要传递 `invoices_callback_router.routes` 中的 `.routes` 属性。

///

### 查看文档

    e: IOException,
  )

  /**
   * Called when the HTTP response was successfully returned by the remote server. The callback may
   * proceed to read the response body with [Response.body]. The response is still live until its
   * response body is [closed][ResponseBody]. The recipient of the callback may consume the response
   * body on another thread.
   *

   * java.util.concurrent.CompletableFuture#thenAcceptAsync}.
   *
   * @param callback The callback to invoke when this {@code Future} is completed.
   * @param executor The executor to run {@code callback} when the future completes.
   */
  public final void addCallback(FutureCallback<? super V> callback, Executor executor) {
    Futures.addCallback(this, callback, executor);
  }

   *
   * @param future The future attach the callback to.
   * @param callback The callback to invoke when {@code future} is completed.
   * @param executor The executor to run {@code callback} when the future completes.
   * @since 10.0
   */
  public static <V extends @Nullable Object> void addCallback(
      final ListenableFuture<V> future,
      final FutureCallback<? super V> callback,
      Executor executor) {

			callbacks: []callback{{h: c1}, {h: c2, before: "c4", after: "c5"}, {h: c3, before: "c4", after: "*"}, {h: c4, after: "*"}, {h: c5, before: "*"}},
			results:   []string{"c5", "c1", "c2", "c3", "c4"},
		},
	}

	for idx, data := range datas {
		db, err := gorm.Open(nil, nil)
		if err != nil {
			t.Fatal(err)
		}
		callbacks := db.Callback()

		for _, c := range data.callbacks {
			var v interface{} = callbacks.Create()

  TFE_CancelCallback callback1;
  callback1.callback = [](void* context) {
    ADD_FAILURE() << "Callback1 should be deregistered.";
  };
  TFE_CancellationToken token1 = TFE_CancellationManagerGetToken(c_mgr);
  EXPECT_TRUE(TFE_CancellationManagerRegisterCallback(c_mgr, token1, &callback1,
                                                      "callback1"));

  TFE_CancelCallback callback2;

                Request.Builder()
                  .url(server.url("/a"))
                  .build()
              try {
                val callbackA = RecordingCallback()
                client.newCall(requestA).enqueue(callbackA)
                callbackA.await(requestA.url).assertBody("a")
              } catch (e: Exception) {
                throw RuntimeException(e)
              }
            }