saving*. SQLModel understands that the database will provide the `id` and *defines the column as a non-null `INTEGER`* in the database schema. See <a href="https://sqlmodel.tiangolo.com/tutorial/create-db-and-table/#primary-key-id" class="external-link" target="_blank">SQLModel docs on primary keys</a> for details.

* `Field(index=True)` tells SQLModel that it should create a **SQL index** for this column, that would allow faster lookups in the database when reading data filtered by this column....

        return data
    ```

    Note that for OAuth2 the scope `items:read` is a single scope in an opaque string.
    You could have custom internal logic to separate it by colon characters (`:`) or
    similar, and get the two parts `items` and `read`. Many applications do that to
    group and organize permissions, you could do it as well in your application, just
    know that that it is application specific, it's not part of the specification.
    """

///

And then the `admin_email` setting would be set to `"******@****.***"`.

The `app_name` would be `"ChimichangApp"`.

And the `items_per_user` would keep its default value of `50`.

## Settings in another module { #settings-in-another-module }

That way the session would release the database connection, so other requests could use it.

And then, you could give that JWT token to a user (or bot), and they could use it to perform those actions (drive the car, or edit the blog post) without even needing to have an account, just with the JWT token your API generated for that.

Using these ideas, JWT can be used for way more sophisticated scenarios.

In those cases, several of those entities could have the same ID, let's say `foo` (a user `foo`, a car `foo`, and a blog post `foo`).

Now, let's see how you could use that to return a custom response.

Let's say that you want to return an <a href="https://en.wikipedia.org/wiki/XML" class="external-link" target="_blank">XML</a> response.

But for the generated client, we could **modify** the OpenAPI operation IDs right before generating the clients, just to make those method names nicer and **cleaner**.

We could download the OpenAPI JSON to a file `openapi.json` and then we could **remove that prefixed tag** with a script like this:

{* ../../docs_src/generate_clients/tutorial004_py39.py *}

Nevertheless, it is already being used as a "standard" by several tools. This greatly improves interoperability, as you could switch Uvicorn for any other ASGI server (like Daphne or Hypercorn), or you could add ASGI compatible tools, like `python-socketio`.

///

/// check | **FastAPI** uses it to

Handle all the core web parts. Adding features on top.

{* ../../docs_src/dependencies/tutorial008_an_py39.py hl[18:19,26:27] *}

The same way, you could have some dependencies with `yield` and some other dependencies with `return`, and have some of those depend on some of the others.

And you could have a single dependency that requires several other dependencies with `yield`, etc.

You can have any combinations of dependencies that you want.

# OpenAPI Callbacks { #openapi-callbacks }

You could create an API with a *path operation* that could trigger a request to an *external API* created by someone else (probably the same developer that would be *using* your API).