# Usando Dataclasses { #using-dataclasses }

FastAPI está construido sobre **Pydantic**, y te he estado mostrando cómo usar modelos de Pydantic para declarar requests y responses.

Pero FastAPI también soporta el uso de <a href="https://docs.python.org/3/library/dataclasses.html" class="external-link" target="_blank">`dataclasses`</a> de la misma manera:

{* ../../docs_src/dataclasses_/tutorial001_py310.py hl[1,6:11,18:19] *}

    /**
     * {@inheritDoc}
     *
     * @see jcifs.util.transport.Response#setExpiration(java.lang.Long)
     */
    @Override
    public void setExpiration(final Long exp) {
        this.expiration = exp;
    }

    /**
     * Checks whether the asynchronous interim response has been handled.
     *
     * @return whether the interim response has been handled
     */
    public boolean isAsyncHandled() {

def test_header_param_model(client: TestClient):
    response = client.get(
        "/items/",
        headers=[
            ("save-data", "true"),
            ("if-modified-since", "yesterday"),
            ("traceparent", "123"),
            ("x-tag", "one"),
            ("x-tag", "two"),
        ],
    )
    assert response.status_code == 200, response.text
    assert response.json() == {
        "host": "testserver",

    }


def test_query_param_model_defaults(client: TestClient):
    response = client.get("/items/")
    assert response.status_code == 200
    assert response.json() == {
        "limit": 100,
        "offset": 0,
        "order_by": "created_at",
        "tags": [],
    }


def test_query_param_model_invalid(client: TestClient):
    response = client.get(
        "/items/",
        params={
            "limit": 150,

def test_security_http_basic():
    response = client.get("/users/me", auth=("john", "secret"))
    assert response.status_code == 200, response.text
    assert response.json() == {"username": "john", "password": "secret"}


def test_security_http_basic_no_credentials():
    response = client.get("/users/me")
    assert response.json() == {"detail": "Not authenticated"}
    assert response.status_code == 401, response.text

    response = client.get("/items/")
    assert response.status_code == 200
    assert response.json() == {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}


def test_query_params_str_validations_q_empty_str(client: TestClient):
    response = client.get("/items/", params={"q": ""})
    assert response.status_code == 200
    assert response.json() == {"items": [{"item_id": "Foo"}, {"item_id": "Bar"}]}

client = TestClient(app)


def test_multi_query():
    response = client.get("/items/?q=5&q=6")
    assert response.status_code == 200, response.text
    assert response.json() == {"q": [5, 6]}


def test_multi_query_incorrect():
    response = client.get("/items/?q=five&q=six")
    assert response.status_code == 422, response.text
    assert response.json() == {
        "detail": [
            {

    enforce strict null checks.

 *  New: The response message is now non-null. This is the "Not Found" in the
    status line "HTTP 404 Not Found". If you are building responses
    programmatically (with `new Response.Builder()`) you must now always supply
    a message. An empty string `""` is permitted. This value was never null on
    responses returned by OkHttp itself, and it was an old mistake to permit

    },
}


def test_schema():
    response = client.get("/openapi.json")
    assert response.status_code == status.HTTP_200_OK
    actual_schema = response.json()
    assert actual_schema == expected_schema


def test_get_invalid():
    response = client.get("/foo")
    assert response.status_code == 422


def test_get_valid():
    response = client.get("/foo", params={"client_id": "bar"})

    }


def test_openapi_schema(client: TestClient):
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {"title": "FastAPI", "version": "0.1.0"},
        "paths": {
            "/items/": {
                "get": {
                    "responses": {
                        "200": {