First, write all your **FastAPI** application as normally:

{* ../../docs_src/extending_openapi/tutorial001_py39.py hl[1,4,7:9] *}

### Generate the OpenAPI schema { #generate-the-openapi-schema }

Then, use the same utility function to generate the OpenAPI schema, inside a `custom_openapi()` function:

{* ../../docs_src/extending_openapi/tutorial001_py39.py hl[2,15:21] *}

### Modify the OpenAPI schema { #modify-the-openapi-schema }

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

### Подприложение { #sub-application }

Затем создайте подприложение и его *операции пути*.

Это подприложение — обычное стандартное приложение FastAPI, но именно оно будет «смонтировано»:

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

### Смонтируйте подприложение { #mount-the-sub-application }

{* ../../docs_src/path_params/tutorial003_py39.py hl[6,11] *}

Otherwise, the path for `/users/{user_id}` would match also for `/users/me`, "thinking" that it's receiving a parameter `user_id` with a value of `"me"`.

Similarly, you cannot redefine a path operation:

{* ../../docs_src/path_params/tutorial003b_py39.py hl[6,11] *}

The first one will always be used since the path matches first.

{* ../../docs_src/path_params/tutorial003_py39.py hl[6,11] *}

De lo contrario, el path para `/users/{user_id}` también coincidiría para `/users/me`, "pensando" que está recibiendo un parámetro `user_id` con un valor de `"me"`.

De manera similar, no puedes redefinir una path operation:

{* ../../docs_src/path_params/tutorial003b_py39.py hl[6,11] *}

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

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

Luego, crea tu sub-aplicación, y sus *path operations*.

Esta sub-aplicación es solo otra aplicación estándar de FastAPI, pero es la que se "montará":

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

### Montar la sub-aplicación { #mount-the-sub-application }

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

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

Em seguida, crie sua sub-aplicação e suas *operações de rota*.

Essa sub-aplicação é apenas outra aplicação FastAPI padrão, mas esta é a que será "montada":

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

### Monte a sub-aplicação { #mount-the-sub-application }

from docs_src.generate_clients import tutorial003_py39


def test_remove_tags(tmp_path: pathlib.Path):
    tmp_file = tmp_path / "openapi.json"
    openapi_json = tutorial003_py39.app.openapi()
    tmp_file.write_text(json.dumps(openapi_json))

    with patch("pathlib.Path", return_value=tmp_file):
        importlib.import_module("docs_src.generate_clients.tutorial004_py39")

{* ../../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] *}

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,),