Endpoint with responses with different status codes

[Xemnas0]

Litestar version: 2.0.0b4
Pydantic version: 2.1.1

I've been trying to create an endpoint that returns different status codes depending on the outcome of the call.

from litestar import Litestar, get, status_codes
from litestar.openapi import ResponseSpec
from pydantic import BaseModel


class User(BaseModel):
    id: str


class NotFoundResponse(BaseModel):
    message: str


@get(
    path="/user/{user_id:str}",
    responses={
        status_codes.HTTP_200_OK: ResponseSpec(data_container=User),
        status_codes.HTTP_404_NOT_FOUND: ResponseSpec(data_container=NotFoundResponse),
    },
)
def get_user(user_id: str) -> User:
    if user_id == "null":
        return NotFoundResponse(message="not found")
    return User(id=user_id)


app = Litestar(route_handlers=[get_user])

The above code fails with the following errore

INFO:     Started server process [66800]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8080 (Press CTRL+C to quit)
ERROR - 2023-08-01 16:44:26,204 - litestar - config - exception raised on http connection to route /schema/swagger

Traceback (most recent call last):
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/serialization/msgspec_hooks.py", line 141, in encode_json
    return msgspec.json.encode(value, enc_hook=serializer) if serializer else _msgspec_json_encoder.encode(value)
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/serialization/msgspec_hooks.py", line 88, in default_serializer
    raise TypeError(f"Unsupported type: {type(value)!r}")
TypeError: Unsupported type: <class 'app.User'>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/middleware/exceptions/middleware.py", line 157, in __call__
    await self.app(scope, receive, send)
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/routes/http.py", line 77, in handle
    response = await self._get_response_for_request(
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/routes/http.py", line 129, in _get_response_for_request
    response = await self._call_handler_function(
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/routes/http.py", line 158, in _call_handler_function
    response_data, cleanup_group = await self._get_response_data(
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/routes/http.py", line 204, in _get_response_data
    data = route_handler.fn.value(**parsed_kwargs)
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/openapi/controller.py", line 209, in swagger_ui
    return ASGIResponse(body=self.render_swagger_ui(request), media_type=MediaType.HTML)
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/openapi/controller.py", line 275, in render_swagger_ui
    spec: {encode_json(schema.to_schema()).decode("utf-8")},
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/serialization/msgspec_hooks.py", line 143, in encode_json
    raise SerializationException(str(msgspec_error)) from msgspec_error
litestar.exceptions.base_exceptions.SerializationException: Unsupported type: <class 'app.User'>
Traceback (most recent call last):
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/serialization/msgspec_hooks.py", line 141, in encode_json
    return msgspec.json.encode(value, enc_hook=serializer) if serializer else _msgspec_json_encoder.encode(value)
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/serialization/msgspec_hooks.py", line 88, in default_serializer
    raise TypeError(f"Unsupported type: {type(value)!r}")
TypeError: Unsupported type: <class 'app.User'>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/middleware/exceptions/middleware.py", line 157, in __call__
    await self.app(scope, receive, send)
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/routes/http.py", line 77, in handle
    response = await self._get_response_for_request(
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/routes/http.py", line 129, in _get_response_for_request
    response = await self._call_handler_function(
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/routes/http.py", line 158, in _call_handler_function
    response_data, cleanup_group = await self._get_response_data(
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/routes/http.py", line 204, in _get_response_data
    data = route_handler.fn.value(**parsed_kwargs)
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/openapi/controller.py", line 209, in swagger_ui
    return ASGIResponse(body=self.render_swagger_ui(request), media_type=MediaType.HTML)
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/openapi/controller.py", line 275, in render_swagger_ui
    spec: {encode_json(schema.to_schema()).decode("utf-8")},
  File "/home/myuser/projects/litestar-test/.venv/lib/python3.10/site-packages/litestar/serialization/msgspec_hooks.py", line 143, in encode_json
    raise SerializationException(str(msgspec_error)) from msgspec_error
litestar.exceptions.base_exceptions.SerializationException: Unsupported type: <class 'app.User'>
INFO:     127.0.0.1:44104 - "GET /schema/swagger HTTP/1.1" 500 Internal Server Error

However, if I use dataclasses (as the code below)

from litestar import Litestar, get, status_codes
from litestar.openapi import ResponseSpec
from dataclasses import dataclass


@dataclass
class User:
    id: str


@dataclass
class NotFoundResponse:
    message: str


@get(
    path="/user/{user_id:str}",
    responses={
        status_codes.HTTP_200_OK: ResponseSpec(data_container=User),
        status_codes.HTTP_404_NOT_FOUND: ResponseSpec(data_container=NotFoundResponse),
    },
)
def get_user(user_id: str) -> User:
    if user_id == "null":
        return NotFoundResponse(message="not found")
    return User(id=user_id)


app = Litestar(route_handlers=[get_user])

The result is the following

Is this a bug?

The schema shown in the responses does not directly correspond to the schema of the dataclasses. How can I make them the same?

[Goldziher]

Looks like a bug to me.

[Xemnas0]

Should I open an issue for this? Or this discussion is enough?

[provinzkraut]

An issue would be appropriate!