"user": {"username": "Dave"},
        },
    )
    assert response.status_code == 200
    assert response.json() == {
        "item_id": 5,
        "importance": 2,
        "item": {
            "name": "Foo",
            "price": 50.5,
            "description": None,
            "tax": None,
        },
        "user": {"username": "Dave", "full_name": None},
    }

This change also meant that if you returned a `StreamingResponse`, the exit code of the dependency with `yield` would have been already run.

For example, if you had a database session in a dependency with `yield`, the `StreamingResponse` would not be able to use that session while streaming data because the session would have already been closed in the exit code after `yield`.

                            },
                            {
                                "name": "save-data",
                                "in": "header",
                                "required": True,
                                "schema": {"type": "boolean", "title": "Save Data"},
                            },
                            {
                                "name": "if-modified-since",

                            },
                            {
                                "name": "save-data",
                                "in": "header",
                                "required": True,
                                "schema": {"type": "boolean", "title": "Save Data"},
                            },
                            {
                                "name": "if-modified-since",

        "traceparent": "123",
        "x_tag": ["one", "two"],
    }


def test_header_param_model_no_underscore(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 == 422

            bool,
            Doc(
                """
                Configuration passed to Pydantic to define if the response data
                should have all the fields, including the ones that were not set and
                have their default values. This is different from
                `response_model_exclude_defaults` in that if the fields are set,

        {
            "openapi": "3.1.0",
            "info": {"title": "FastAPI", "version": "0.1.0"},
            "paths": {
                "/items/": {
                    "post": {
                        "summary": "Save Union Body Discriminator",
                        "operationId": "save_union_body_discriminator_items__post",
                        "parameters": [
                            {
                                "name": "q",

                    "operationId": "read_items_items__get",
                    "parameters": [
                        {
                            "description": "Query string for the items to search in the database that have a good match",
                            "required": False,
                            "deprecated": True,
                            "schema": {
                                "anyOf": [

    @property
    def __dict__(self):
        """Spoof a missing __dict__ by raising TypeError, this is how
        asyncpg.pgroto.pgproto.UUID behaves"""
        raise TypeError("vars() argument must have __dict__ attribute")


def test_pydanticv2():
    from pydantic import field_serializer

    app = FastAPI()

    @app.get("/fast_uuid")
    def return_fast_uuid():

                                    }
                                }
                            },
                        },
                    },
                    "summary": "Save Union Body",
                    "operationId": "save_union_body_items__post",
                    "requestBody": {
                        "content": {
                            "application/json": {