```Python hl_lines="9"
    {!> ../../../docs_src/header_params/tutorial001.py!}
    ```

!!! note "Technical Details"
    `Header` is a "sister" class of `Path`, `Query` and `Cookie`. It also inherits from the same common `Param` class.

    But remember that when you import `Query`, `Path`, `Header`, and others from `fastapi`, those are actually functions that return special classes.

!!! info

We will create a `PeeweeConnectionState`:

```Python hl_lines="10-19"
{!../../../docs_src/sql_databases_peewee/sql_app/database.py!}
```

This class inherits from a special internal class used by Peewee.

It has all the logic to make Peewee use `contextvars` instead of `threading.local`.

INHERIT: ../en/mkdocs.yml...

INHERIT: ../en/mkdocs.yml...

    "size": "XL"
  }
}
```

#### FastAPI's `HTTPException` vs Starlette's `HTTPException`

**FastAPI** has its own `HTTPException`.

And **FastAPI**'s `HTTPException` error class inherits from Starlette's `HTTPException` error class.

The only difference is that **FastAPI**'s `HTTPException` accepts any JSON-able data for the `detail` field, while Starlette's `HTTPException` only accepts strings for it.

Check the in-code annotation tips above to see more specific details.

## Learn More

You can also combine `dataclasses` with other Pydantic models, inherit from them, include them in your own models, etc.

To learn more, check the <a href="https://docs.pydantic.dev/latest/concepts/dataclasses/" class="external-link" target="_blank">Pydantic docs about dataclasses</a>.

## Version

        )


class OAuth2(SecurityBase):
    """
    This is the base class for OAuth2 authentication, an instance of it would be used
    as a dependency. All other OAuth2 classes inherit from it and customize it for
    each OAuth2 flow.

    You normally would not create a new class inheriting from it but use one of the
    existing subclasses, and maybe compose them if you want to support multiple flows.

Sebastián Ramírez <******@****.***> 1688749933 +0200

INHERIT: ../en/mkdocs.yml...

INHERIT: ../en/mkdocs.yml...