!!! check "**FastAPI** uses it to"
    Handle all the core web parts. Adding features on top.

    The class `FastAPI` itself inherits directly from the class `Starlette`.

If you are curious about how the raw OpenAPI schema looks like, FastAPI automatically generates a JSON (schema) with the descriptions of all your API.

You can see it directly at: <a href="http://127.0.0.1:8000/openapi.json" class="external-link" target="_blank">http://127.0.0.1:8000/openapi.json</a>.

It will show a JSON starting with something like:

```JSON
{
    "openapi": "3.1.0",
    "info": {
        "title": "FastAPI",

## Additional servers

!!! warning
    This is a more advanced use case. Feel free to skip it.

By default, **FastAPI** will create a `server` in the OpenAPI schema with the URL for the `root_path`.

But you can also provide other alternative `servers`, for example if you want *the same* docs UI to interact with a staging and production environments.

!!! tip
    You can <a href="https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/commenting-on-a-pull-request" class="external-link" target="_blank">add comments with change suggestions</a> to existing pull requests.

You can see those schemas because they were declared with the models in the app.

That information is available in the app's **OpenAPI schema**, and then shown in the API docs (by Swagger UI).

And that same information from the models that is included in OpenAPI is what can be used to **generate the client code**.

### Generate a TypeScript Client

Now that we have the app with the models, we can generate the client code for the frontend.

#### Data with values for fields with defaults

But if your data has values for the model's fields with default values, like the item with ID `bar`:

```Python hl_lines="3  5"
{
    "name": "Bar",
    "description": "The bartenders",
    "price": 62,
    "tax": 20.2
}
```

they will be included in the response.

#### Data with the same values as the defaults

        ],
        scope: Annotated[
            str,
            Form(),
            Doc(
                """
                A single string with actually several scopes separated by spaces. Each
                scope is also a string.

                For example, a single string with:

                ```python
                "items:read items:write users:read profile openid"
                ````

    }


@needs_py310
def test_post_with_str_float(client: TestClient):
    response = client.post("/items/", json={"name": "Foo", "price": "50.5"})
    assert response.status_code == 200
    assert response.json() == {
        "name": "Foo",
        "price": 50.5,
        "description": None,
        "tax": None,
    }


@needs_py310
def test_post_with_str_float_description(client: TestClient):

        "tax": None,
    }


def test_post_with_str_float(client: TestClient):
    response = client.post("/items/", json={"name": "Foo", "price": "50.5"})
    assert response.status_code == 200
    assert response.json() == {
        "name": "Foo",
        "price": 50.5,
        "description": None,
        "tax": None,
    }


def test_post_with_str_float_description(client: TestClient):

                },
            ]
        }
    )


def test_items_with_invalid_token(client: TestClient):
    response = client.get("/items?token=jessica", headers={"X-Token": "invalid"})
    assert response.status_code == 400
    assert response.json() == {"detail": "X-Token header invalid"}


def test_items_bar_with_invalid_token(client: TestClient):