"type": "type_error.integer",
                }
            ]
        }
    )


def test_query_int_query_baz():
    response = client.get("/query/int?query=baz")
    assert response.status_code == 422
    assert response.json() == IsDict(
        {
            "detail": [
                {
                    "type": "int_parsing",

# Response Model - Return Type

You can declare the type used for the response by annotating the *path operation function* **return type**.

You can use **type annotations** the same way you would for input data in function **parameters**, you can use Pydantic models, lists, dictionaries, scalar values like integers, booleans, etc.

=== "Python 3.10+"

    ```Python hl_lines="16  21"
    {!> ../../../docs_src/response_model/tutorial001_01_py310.py!}
    ```

                        "type": "string"
                    },
                    "type": {
                        "title": "Error Type",
                        "type": "string"
                    }
                }
            },
            "HTTPValidationError": {
                "title": "HTTPValidationError",
                "type": "object",
                "properties": {

class ResponseLevel0(JSONResponse):
    media_type = "application/x-level-0"


class ResponseLevel1(JSONResponse):
    media_type = "application/x-level-1"


class ResponseLevel2(JSONResponse):
    media_type = "application/x-level-2"


class ResponseLevel3(JSONResponse):
    media_type = "application/x-level-3"


class ResponseLevel4(JSONResponse):
    media_type = "application/x-level-4"

                "Error": {
                    "title": "Error",
                    "required": ["status", "title"],
                    "type": "object",
                    "properties": {
                        "status": {"title": "Status", "type": "string"},
                        "title": {"title": "Title", "type": "string"},
                    },
                },
                "JsonApiError": {

                "Error": {
                    "title": "Error",
                    "required": ["status", "title"],
                    "type": "object",
                    "properties": {
                        "status": {"title": "Status", "type": "string"},
                        "title": {"title": "Title", "type": "string"},
                    },
                },
                "JsonApiError": {
                    "title": "JsonApiError",

from fastapi.testclient import TestClient
from starlette.routing import Route

app = FastAPI()


class APIRouteA(APIRoute):
    x_type = "A"


class APIRouteB(APIRoute):
    x_type = "B"


class APIRouteC(APIRoute):
    x_type = "C"


router_a = APIRouter(route_class=APIRouteA)
router_b = APIRouter(route_class=APIRouteB)
router_c = APIRouter(route_class=APIRouteC)

                "Rectangle": {
                    "properties": {
                        "width": {"type": "integer", "title": "Width"},
                        "length": {"type": "integer", "title": "Length"},
                        "area": {"type": "integer", "title": "Area", "readOnly": True},
                    },
                    "type": "object",
                    "required": ["width", "length", "area"],

        set[int]: [1, 2, 3],  # `set` is converted to `list`
        tuple[int, ...]: [1, 2, 3],  # `tuple` is converted to `list`
    }
    for test_type, expect in types.items():
        app = FastAPI()

        @app.post("/", response_model=test_type)
        def post_endpoint(input: test_type):
            return input

        res = TestClient(app).post("/", json=expect)
        assert res.status_code == 200, res.json()

```JSON
{"item_id":"foo"}
```

## Path parameters with types

You can declare the type of a path parameter in the function, using standard Python type annotations:

```Python hl_lines="7"
{!../../../docs_src/path_params/tutorial002.py!}
```

In this case, `item_id` is declared to be an `int`.

!!! check