@router.route("/items/")
def read_items(request: Request):
    return JSONResponse({"hello": "world"})


app.include_router(router)

client = TestClient(app)


def test_sub_router():
    response = client.get("/items/")
    assert response.status_code == 200, response.text

### Create it

* Create a file `main.py` with:

```Python
from typing import Union

from fastapi import FastAPI

app = FastAPI()


@app.get("/")
def read_root():
    return {"Hello": "World"}


@app.get("/items/{item_id}")
def read_item(item_id: int, q: Union[str, None] = None):
    return {"item_id": item_id, "q": q}
```

<details markdown="1">

    # Code below omitted 👇
    ```

    <details>
    <summary>👀 Full file preview</summary>

    ```Python
    {!> ../../../docs_src/separate_openapi_schemas/tutorial001_py310.py!}
    ```

    </details>

=== "Python 3.9+"

    ```Python hl_lines="16"
    {!> ../../../docs_src/separate_openapi_schemas/tutorial001_py39.py[ln:1-17]!}

    # Code below omitted 👇
    ```

    <details>

    $ export MY_NAME="Wade Wilson"

    // 然后您可以与其他程序一起使用它，例如
    $ echo "Hello $MY_NAME"

    Hello Wade Wilson
    ```

    </div>

=== "Windows PowerShell"

    <div class="termy">

    ```console
    // 创建一个名为 MY_NAME 的环境变量
    $ $Env:MY_NAME = "Wade Wilson"

    // 与其他程序一起使用它，例如
    $ echo "Hello $Env:MY_NAME"

    Hello Wade Wilson
    ```

    </div>

### 在 Python 中读取环境变量

```txt
Hello, World from Flask!
```

And if you go to <a href="http://localhost:8000/v2" class="external-link" target="_blank">http://localhost:8000/v2</a> you will see the response from FastAPI:

```JSON
{
    "message": "Hello World"
}

```Python
    first_name="john", last_name="doe"
```

Es algo diferente.

Estamos usando los dos puntos (`:`), no un símbolo de igual (`=`).

Añadir los type hints normalmente no cambia lo que sucedería si ellos no estuviesen presentes.

Pero ahora imagina que nuevamente estás creando la función, pero con los type hints.

En el mismo punto intentas iniciar el auto-completado con `Ctrl+Space` y ves:

app = FastAPI()


@app.api_route("/api_route")
def non_operation():
    return {"message": "Hello World"}


def non_decorated_route():
    return {"message": "Hello World"}


app.add_api_route("/non_decorated_route", non_decorated_route)


@app.get("/text")
def get_text():
    return "Hello World"


@app.get("/path/{item_id}")
def get_id(item_id):
    return item_id

from fastapi import FastAPI

app = FastAPI(swagger_ui_parameters={"deepLinking": False})


@app.get("/users/{username}")
async def read_user(username: str):

app = FastAPI()

app.add_middleware(
    TrustedHostMiddleware, allowed_hosts=["example.com", "*.example.com"]
)


@app.get("/")
async def main():

class Settings(BaseSettings):
    openapi_url: str = "/openapi.json"


settings = Settings()

app = FastAPI(openapi_url=settings.openapi_url)


@app.get("/")
def root():