<img src="/img/tutorial/body/image04.png">

This is not by chance, the whole framework was built around that design.

And it was thoroughly tested at the design phase, before any implementation, to ensure it would work with all the editors.

There were even some changes to Pydantic itself to support this.

Each section gradually builds on the previous ones, but it's structured to separate topics, so that you can go directly to any specific one to solve your specific API needs.

It is also built to work as a future reference.

So you can come back and see exactly what you need.

## Run the code

All the code blocks can be copied and used directly (they are actually tested Python files).

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.

Common ORMs are for example: Django-ORM (part of the Django framework), SQLAlchemy ORM (part of SQLAlchemy, independent of framework) and Peewee (independent of framework), among others.

Here we will see how to work with **SQLAlchemy ORM**.

## Replication - Number of Processes

    You can consider this a brief OpenAPI and JSON Schema **history lesson**. 🤓

!!! warning
    These are very technical details about the standards **JSON Schema** and **OpenAPI**.

    If the ideas above already work for you, that might be enough, and you probably don't need these details, feel free to skip them.

Before OpenAPI 3.1.0, OpenAPI used an older and modified version of **JSON Schema**.

    * Check that it has a required attribute `price` that has to be a `float`.
    * Check that it has an optional attribute `is_offer`, that should be a `bool`, if present.
    * All this would also work for deeply nested JSON objects.
* Convert from and to JSON automatically.
* Document everything with OpenAPI, that can be used by:
    * Interactive documentation systems.

```

`async def`를 사용하면, 파이썬은 해당 함수 내에서 `await` 표현에 주의해야한다는 사실과, 해당 함수의 실행을 "일시정지"⏸하고 다시 돌아오기 전까지 다른 작업을 수행🔀할 수 있다는 것을 알게됩니다.

`async def`f 함수를 호출하고자 할 때, "대기"해야합니다. 따라서, 아래는 동작하지 않습니다.

```Python
# This won't work, because get_burgers was defined with: async def
burgers = get_burgers(2)
```

---

따라서, `await`f를 사용해서 호출할 수 있는 라이브러리를 사용한다면, 다음과 같이 `async def`를 사용하는 *경로 작동 함수*를 생성해야 합니다:

```Python hl_lines="2-3"

        or hasattr(origin, "__get_pydantic_core_schema__")
    )


def field_annotation_is_scalar(annotation: Any) -> bool:
    # handle Ellipsis here to make tuple[int, ...] work nicely
    return annotation is Ellipsis or not field_annotation_is_complex(annotation)


def field_annotation_is_scalar_sequence(annotation: Union[Type[Any], None]) -> bool:
    origin = get_origin(annotation)

!!! tip
    For this to work, you need to `pip install python-dotenv`.

### The `.env` file

You could have a `.env` file with:

```bash
ADMIN_EMAIL="******@****.***"
APP_NAME="ChimichangApp"
```

    * Check that it has a required attribute `price` that has to be a `float`.
    * Check that it has an optional attribute `is_offer`, that should be a `bool`, if present.
    * All this would also work for deeply nested JSON objects.
* Convert from and to JSON automatically.
* Document everything with OpenAPI, that can be used by:
    * Interactive documentation systems.