```

</div>

It is **HIGHLY encouraged** that you write or copy the code, edit it and run it locally.

Using it in your editor is what really shows you the benefits of FastAPI, seeing how little code you have to write, all the type checks, autocompletion, etc.

---

## Install FastAPI

The first step is to install FastAPI.

---

"_If anyone is looking to build a production Python API, I would highly recommend **FastAPI**. It is **beautifully designed**, **simple to use** and **highly scalable**, it has become a **key component** in our API first development strategy and is driving many automations and services such as our Virtual TAC Engineer._"

    assert "id" in data[0]


@needs_py39
# TODO: pv2 add version with Pydantic v2
@needs_pydanticv1
def test_create_item(client):
    item = {"title": "Foo", "description": "Something that fights"}
    response = client.post("/users/1/items/", json=item)
    assert response.status_code == 200, response.text
    item_data = response.json()
    assert item["title"] == item_data["title"]

    assert "email" in data[0]
    assert "id" in data[0]


@needs_py310
# TODO: pv2 add Pydantic v2 version
@needs_pydanticv1
def test_create_item(client):
    item = {"title": "Foo", "description": "Something that fights"}
    response = client.post("/users/1/items/", json=item)
    assert response.status_code == 200, response.text
    item_data = response.json()
    assert item["title"] == item_data["title"]

    assert "email" in data[0]
    assert "id" in data[0]


@needs_py39
# TODO: pv2 add Pydantic v2 version
@needs_pydanticv1
def test_create_item(client):
    item = {"title": "Foo", "description": "Something that fights"}
    response = client.post("/users/1/items/", json=item)
    assert response.status_code == 200, response.text
    item_data = response.json()
    assert item["title"] == item_data["title"]

And even if you were not using FastAPI, you could also write your own async applications with <a href="https://anyio.readthedocs.io/en/stable/" class="external-link" target="_blank">AnyIO</a> to be highly compatible and get its benefits (e.g. *structured concurrency*).

### Other forms of asynchronous code

This style of using `async` and `await` is relatively new in the language.

Or it might be the case that you just prefer to take other courses because they adapt better to your learning style.

But you can return a `JSONResponse` directly from your *path operations*.

It might be useful, for example, to return custom headers or cookies.

## Return a `Response`

In fact, you can return any `Response` or any sub-class of it.

!!! tip
    `JSONResponse` itself is a sub-class of `Response`.

# Extending OpenAPI

There are some cases where you might need to modify the generated OpenAPI schema.

In this section you will see how.

## The normal process

The normal (default) process, is as follows.

A `FastAPI` application (instance) has an `.openapi()` method that is expected to return the OpenAPI schema.

    You can actually skip that extra header and it would still work.

    But it's provided here to be compliant with the specifications.

    Also, there might be tools that expect and use it (now or in the future) and that might be useful for you or your users, now or in the future.

    That's the benefit of standards...

## See it in action