{* ../../docs_src/sub_applications/tutorial001_py39.py hl[3, 6:8] *}

### Unteranwendung { #sub-application }

Erstellen Sie dann Ihre Unteranwendung und deren *Pfadoperationen*.

Diese Unteranwendung ist nur eine weitere Standard-FastAPI-Anwendung, aber diese wird „gemountet“:

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[11, 14:16] *}

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[3, 6:8] *}

### Sub-application { #sub-application }

Then, create your sub-application, and its *path operations*.

This sub-application is just another standard FastAPI application, but this is the one that will be "mounted":

{* ../../docs_src/sub_applications/tutorial001_py39.py hl[11, 14:16] *}

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[6:9] *}

## Добавление фоновой задачи { #add-the-background-task }

Внутри вашей функции‑обработчика пути передайте функцию задачи объекту фоновых задач методом `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[14] *}

`.add_task()` принимает следующие аргументы:

from unittest.mock import patch

from docs_src.python_types.tutorial008_py39 import process_items


def test_process_items():
    with patch("builtins.print") as mock_print:
        process_items({"a": 1.0, "b": 2.5})

    assert mock_print.call_count == 4
    call_args = [arg.args for arg in mock_print.call_args_list]
    assert call_args == [
        ("a",),
        (1.0,),
        ("b",),
        (2.5,),

import importlib

import pytest
from fastapi.testclient import TestClient


@pytest.fixture(
    name="client",
    params=[
        pytest.param("tutorial008e_py39"),
        pytest.param("tutorial008e_an_py39"),
    ],
)
def get_client(request: pytest.FixtureRequest):
    mod = importlib.import_module(f"docs_src.dependencies.{request.param}")

    client = TestClient(mod.app)
    return client

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[6:9] *}

## Add the background task { #add-the-background-task }

Inside of your *path operation function*, pass your task function to the *background tasks* object with the method `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[14] *}

`.add_task()` receives as arguments:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[6:9] *}

## Adicione a tarefa em segundo plano { #add-the-background-task }

Dentro da sua *função de operação de rota*, passe sua função de tarefa para o objeto de *tarefas em segundo plano* com o método `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001_py39.py hl[14] *}

O `.add_task()` recebe como argumentos:

from fastapi.testclient import TestClient

from docs_src.custom_response.tutorial009c_py39 import app

client = TestClient(app)


def test_get():
    response = client.get("/")

from types import ModuleType

import pytest
from fastapi.exceptions import FastAPIError
from fastapi.testclient import TestClient


@pytest.fixture(
    name="mod",
    params=[
        pytest.param("tutorial008c_py39"),
        pytest.param("tutorial008c_an_py39"),
    ],
)
def get_mod(request: pytest.FixtureRequest):
    mod = importlib.import_module(f"docs_src.dependencies.{request.param}")

    return mod

from fastapi.testclient import TestClient

from docs_src.response_cookies.tutorial001_py39 import app

client = TestClient(app)


def test_path_operation():
    response = client.post("/cookie/")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Come to the dark side, we have cookies"}