"content": {
                            "application/json": {



...
```

#### What is OpenAPI for

The OpenAPI schema is what powers the two interactive documentation systems included.

And there are dozens of alternatives, all based on OpenAPI. You could easily add any of those alternatives to your application built with **FastAPI**.

> Modern versions of Python have support for **"asynchronous code"** using something called **"coroutines"**, with **`async` and `await`** syntax.

That should make more sense now. ✨

All that is what powers FastAPI (through Starlette) and what makes it have such an impressive performance.

## Very Technical Details

!!! warning
    You can probably skip this.

!!! tip
    This will just make Peewee behave correctly when used with FastAPI. Not randomly opening or closing connections that are being used, creating errors, etc.

    But it doesn't give Peewee async super-powers. You should still use normal `def` functions and not `async def`.

### Use the custom `PeeweeConnectionState` class

        Prefer to use the `Annotated` version if possible.

    ```Python hl_lines="9"
    {!> ../../../docs_src/query_params_str_validations/tutorial006c.py!}
    ```

!!! tip

Because this code is executed before the application **starts** taking requests, and right after it **finishes** handling requests, it covers the whole application **lifespan** (the word "lifespan" will be important in a second 😉).

So, `orion_cat.owner.name` could be the name (from the `name` column in the `owners` table) of this pet's owner.

It could have a value like `"Arquilian"`.

And the ORM will do all the work to get the information from the corresponding table *owners* when you try to access it from your pet object.

    username: str


class ModelC(ModelB):
    password: str


class ModelA(BaseModel):
    name: str
    description: Optional[str] = None
    model_b: ModelB

    @validator("name")
    def lower_username(cls, name: str, values):
        if not name.endswith("A"):
            raise ValueError("name must end in A")
        return name


async def get_model_c() -> ModelC:

## OAuth2

OAuth2 is a specification that defines several ways to handle authentication and authorization.

It is quite an extensive specification and covers several complex use cases.

It includes ways to authenticate using a "third party".

That's what all the systems with "login with Facebook, Google, Twitter, GitHub" use underneath.

### OAuth 1

  - login: DMantis
    avatarUrl: https://avatars.githubusercontent.com/u/9536869?v=4
    url: https://github.com/DMantis
  - login: hard-coders
    avatarUrl: https://avatars.githubusercontent.com/u/9651103?u=95db33927bbff1ed1c07efddeb97ac2ff33068ed&v=4
    url: https://github.com/hard-coders
  - login: supdann
    avatarUrl: https://avatars.githubusercontent.com/u/9986994?u=9671810f4ae9504c063227fee34fd47567ff6954&v=4

To declare a **request** body, you use <a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> models with all their power and benefits.

!!! info
    To send data, you should use one of: `POST` (the more common), `PUT`, `DELETE` or `PATCH`.