Each of those response `dict`s can have a key `model`, containing a Pydantic model, just like `response_model`.

**FastAPI** will take that model, generate its JSON Schema and include it in the correct place in OpenAPI.

For example, to declare another response with a status code `404` and a Pydantic model `Message`, you can write:

```Python hl_lines="18  22"

An example could be that you have an external authentication provider that you need to call.

You send it a token and it returns an authenticated user.

This provider might be charging you per request, and calling it might take some extra time than if you had a fixed mock user for tests.

You probably want to test the external provider once, but not necessarily call it for every test that runs.

  - url: https://www.svix.com/
    title: Svix - Webhooks as a service
    img: https://fastapi.tiangolo.com/img/sponsors/svix.svg
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    title: Take code reviews from hours to minutes
    img: https://fastapi.tiangolo.com/img/sponsors/codacy.png
bronze:
  - url: https://www.exoflare.com/open-source/?utm_source=FastAPI&utm_campaign=open_source

        "foo"
    ]
}
```

## Recap

Declare headers with `Header`, using the same common pattern as `Query`, `Path` and `Cookie`.

The same models are shared among requests, so, it's not one model per request, or one per user or something similar.

Let's imagine that loading the model can **take quite some time**, because it has to read a lot of **data from disk**. So you don't want to do it for every request.

From the list of deployment concepts from above, using workers would mainly help with the **replication** part, and a little bit with the **restarts**, but you still need to take care of the others:

* **Security - HTTPS**
* **Running on startup**
* ***Restarts***

That's what makes it possible to have multiple automatic interactive documentation interfaces, code generation, etc.

OpenAPI has a way to define multiple security "schemes".

By using them, you can take advantage of all these standard-based tools, including these interactive documentation systems.

OpenAPI defines the following security schemes:

* `apiKey`: an application specific key that can come from:

```Python
{
    "name": "Barz",
    "price": 3,
    "description": None,
}
```

because it doesn't include the already stored attribute `"tax": 20.2`, the input model would take the default value of `"tax": 10.5`.

And the data would be saved with that "new" `tax` of `10.5`.

## Partial updates with `PATCH`

    ```

## Request body + path + query parameters

You can also declare **body**, **path** and **query** parameters, all at the same time.

**FastAPI** will recognize each of them and take the data from the correct place.

=== "Python 3.10+"

    ```Python hl_lines="16"
    {!> ../../../docs_src/body/tutorial004_py310.py!}
    ```

=== "Python 3.8+"

    ```Python hl_lines="18"