<img src="/img/python-types/image06.png">

Notice that this means "`one_person` is an **instance** of the class `Person`".

It doesn't mean "`one_person` is the **class** called `Person`".

## Pydantic models

<a href="https://docs.pydantic.dev/" class="external-link" target="_blank">Pydantic</a> is a Python library to perform data validation.

You declare the "shape" of the data as classes with attributes.

class JsonApiResponse(JSONResponse):
    media_type = "application/vnd.api+json"


class Error(BaseModel):
    status: str
    title: str


class JsonApiError(BaseModel):
    errors: typing.List[Error]


@app.get(
    "/a/{id}",
    response_class=JsonApiResponse,
    responses={422: {"description": "Error", "model": JsonApiError}},
)
async def a(id):
    pass  # pragma: no cover

                    "loc": ["body", "file"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "fileb"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "token"],

                            "content": {"application/json": {"schema": {}}},
                        },
                        "422": {
                            "description": "Validation Error",
                            "content": {
                                "application/json": {
                                    "schema": {

                    "loc": ["body", "username"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "password"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
            ]
        }
    )


def test_post_body_json(client: TestClient):

                    "loc": ["body", "item"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "user"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "importance"],

                    "loc": ["body", "item"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "user"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "importance"],

                    "loc": ["body", "item"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "user"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "importance"],

                    "loc": ["body", "grant_type"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "username"],
                    "msg": "field required",
                    "type": "value_error.missing",
                },
                {
                    "loc": ["body", "password"],

def test_get_item_not_found_header():
    response = client.get("/items-header/bar")
    assert response.status_code == 404, response.text
    assert response.headers.get("x-error") == "There goes my error"
    assert response.json() == {"detail": "Item not found"}


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text