{* ../../docs_src/dependencies/tutorial013_an_py310.py ln[30:38] hl[31:33] *}

{* ../../docs_src/dependencies/tutorial015_an_py310.py ln[10:15] hl[12:14] *}


## Включения кода с заголовком { #code-includes-with-title }

{* ../../docs_src/bigger_applications/app_an_py310/routers/users.py hl[1,3] title["app/routers/users.py"] *}

Wie Sie sehen, ist die Funktion mit einem `@asynccontextmanager` versehen.

Dadurch wird die Funktion in einen sogenannten „**asynchronen Kontextmanager**“ umgewandelt.

{* ../../docs_src/events/tutorial003_py310.py hl[1,13] *}

Ein **Kontextmanager** in Python ist etwas, das Sie in einer `with`-Anweisung verwenden können, zum Beispiel kann `open()` als Kontextmanager verwendet werden:

```Python
with open("file.txt") as file:
    file.read()

Якщо придивитися, функція задекорована за допомогою `@asynccontextmanager`.

Це перетворює функцію на так званий «асинхронний менеджер контексту».

{* ../../docs_src/events/tutorial003_py310.py hl[1,13] *}

Менеджер контексту в Python - це те, що можна використовувати в операторі `with`, наприклад, `open()` можна використовувати як менеджер контексту:

```Python
with open("file.txt") as file:
    file.read()
```

First, import `BackgroundTasks` and define a parameter in your *path operation function* with a type declaration of `BackgroundTasks`:

{* ../../docs_src/background_tasks/tutorial001_py310.py hl[1,13] *}

**FastAPI** will create the object of type `BackgroundTasks` for you and pass it as that parameter.

## Create a task function { #create-a-task-function }

Create a function to be run as the background task.

在某些情況下，你可能仍需要使用 Pydantic 版本的 `dataclasses`。例如，當自動產生的 API 文件出現錯誤時。

這種情況下，你可以把標準的 `dataclasses` 直接換成 `pydantic.dataclasses`，它是可直接替換（drop-in replacement）的：

{* ../../docs_src/dataclasses_/tutorial003_py310.py hl[1,4,7:10,13:16,22:24,27] *}

1. 我們仍然從標準的 `dataclasses` 匯入 `field`。
2. `pydantic.dataclasses` 是 `dataclasses` 的可直接替換版本。
3. `Author` dataclass 內含一個 `Item` dataclass 的清單。
4. `Author` dataclass 被用作 `response_model` 參數。

    where an integer (but not int typed) is used. Encoding this as a float
    results in failed round-tripping between encode and parse.
    Our Id type is a prime example of this.

    >>> decimal_encoder(Decimal("1.0"))
    1.0

    >>> decimal_encoder(Decimal("1"))
    1

    >>> decimal_encoder(Decimal("NaN"))
    nan
    """
    exponent = dec_value.as_tuple().exponent
    if isinstance(exponent, int) and exponent >= 0:

    assertThat(Doubles.contains(EMPTY, 1.0)).isFalse();
    assertThat(Doubles.contains(ARRAY1, 2.0)).isFalse();
    assertThat(Doubles.contains(ARRAY234, 1.0)).isFalse();
    assertThat(Doubles.contains(new double[] {-1.0}, -1.0)).isTrue();
    assertThat(Doubles.contains(ARRAY234, 2.0)).isTrue();
    assertThat(Doubles.contains(ARRAY234, 3.0)).isTrue();
    assertThat(Doubles.contains(ARRAY234, 4.0)).isTrue();

        C = GG(C, D, A, B, X[8], 9);
        B = GG(B, C, D, A, X[12], 13);
        A = GG(A, B, C, D, X[1], 3);
        D = GG(D, A, B, C, X[5], 5);
        C = GG(C, D, A, B, X[9], 9);
        B = GG(B, C, D, A, X[13], 13);
        A = GG(A, B, C, D, X[2], 3);
        D = GG(D, A, B, C, X[6], 5);
        C = GG(C, D, A, B, X[10], 9);
        B = GG(B, C, D, A, X[14], 13);
        A = GG(A, B, C, D, X[3], 3);

Primeiro, importe `BackgroundTasks` e defina um parâmetro na sua *função de operação de rota* com uma declaração de tipo `BackgroundTasks`:

{* ../../docs_src/background_tasks/tutorial001_py310.py hl[1,13] *}

O **FastAPI** criará o objeto do tipo `BackgroundTasks` para você e o passará como esse parâmetro.

## Crie uma função de tarefa { #create-a-task-function }

If you check, the function is decorated with an `@asynccontextmanager`.

That converts the function into something called an "**async context manager**".

{* ../../docs_src/events/tutorial003_py310.py hl[1,13] *}

A **context manager** in Python is something that you can use in a `with` statement, for example, `open()` can be used as a context manager:

```Python
with open("file.txt") as file:
    file.read()
```