```

</div>

The response would be something like:

```JSON
{
    "message": "Hello World",
    "root_path": "/api/v1"
}
```

### Setting the `root_path` in the FastAPI app

Alternatively, if you don't have a way to provide a command line option like `--root-path` or equivalent, you can set the `root_path` parameter when creating your FastAPI app:

    response = client.post(
        "/admin/?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Admin getting schwifty"}


def test_admin_invalid_header(client: TestClient):
    response = client.post("/admin/", headers={"X-Token": "invalid"})
    assert response.status_code == 400, response.text

    response = client.post(
        "/admin/?token=jessica", headers={"X-Token": "fake-super-secret-token"}
    )
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Admin getting schwifty"}


@needs_py39
def test_admin_invalid_header(client: TestClient):
    response = client.post("/admin/", headers={"X-Token": "invalid"})
    assert response.status_code == 400, response.text

But you might want to still keep the return type annotation in the function to get the support from tools like editors and type checkers (e.g. mypy).

In this case, you can disable the response model generation by setting `response_model=None`:

=== "Python 3.10+"

    ```Python hl_lines="7"
    {!> ../../../docs_src/response_model/tutorial003_05_py310.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="9"

## Opinie

"_[...] I'm using **FastAPI** a ton these days. [...] I'm actually planning to use it for all of my team's **ML services at Microsoft**. Some of them are getting integrated into the core **Windows** product and some **Office** products._"

## Recensioni

"_[...] I'm using **FastAPI** a ton these days. [...] I'm actually planning to use it for all of my team's **ML services at Microsoft**. Some of them are getting integrated into the core **Windows** product and some **Office** products._"

For example:

```Python hl_lines="6  11"
{!../../../docs_src/conditional_openapi/tutorial001.py!}
```

Here we declare the setting `openapi_url` with the same default of `"/openapi.json"`.

And then we use it when creating the `FastAPI` app.

Then you could disable OpenAPI (including the UI docs) by setting the environment variable `OPENAPI_URL` to the empty string, like:

<div class="termy">

```console

* **Swagger UI**: served at `/docs`.
    * You can set its URL with the parameter `docs_url`.
    * You can disable it by setting `docs_url=None`.
* **ReDoc**: served at `/redoc`.
    * You can set its URL with the parameter `redoc_url`.
    * You can disable it by setting `redoc_url=None`.

For example, to set Swagger UI to be served at `/documentation` and disable ReDoc:

```Python hl_lines="3"

* Take a username.
* Generate a document ID from it.
* Get the document with that ID.
* Put the contents of the document in a `UserInDB` model.

## Mix `Path`, `Query` and body parameters

First, of course, you can mix `Path`, `Query` and request body parameter declarations freely and **FastAPI** will know what to do.

And you can also declare body parameters as optional, by setting the default to `None`:

=== "Python 3.10+"

    ```Python hl_lines="18-20"
    {!> ../../../docs_src/body_multiple_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"