fix: encode response content object returned from an exception handle…

…r. (#3585)

fix: encode response content object returned from a exception handler.

Co-authored-by: Raphael Krupinski <3732079+rafalkrupinski@users.noreply.github.com>
(cherry picked from commit 883ca0a)

litestar/middleware/_internal/exceptions/middleware.py

@@ -23,6 +23,7 @@
     from litestar import Response
     from litestar.app import Litestar
     from litestar.connection import Request
+    from litestar.handlers import BaseRouteHandler
     from litestar.logging import BaseLoggingConfig
     from litestar.types import (
         ASGIApp,
@@ -202,7 +203,11 @@ async def handle_request_exception(
         exception_handler = get_exception_handler(exception_handlers, exc) or self.default_http_exception_handler
         request: Request[Any, Any, Any] = litestar_app.request_class(scope=scope, receive=receive, send=send)
         response = exception_handler(request, exc)
-        await response.to_asgi_response(app=None, request=request)(scope=scope, receive=receive, send=send)
+        route_handler: BaseRouteHandler | None = scope.get("route_handler")
+        type_encoders = route_handler.resolve_type_encoders() if route_handler else litestar_app.type_encoders
+        await response.to_asgi_response(app=None, request=request, type_encoders=type_encoders)(
+            scope=scope, receive=receive, send=send
+        )
 
     @staticmethod
     async def handle_websocket_exception(send: Send, exc: Exception) -> None:

tests/unit/test_middleware/test_exception_handler_middleware.py

@@ -2,6 +2,7 @@
 from typing import TYPE_CHECKING, Any, Callable, Generator, Optional
 from unittest.mock import MagicMock
 
+import pydantic
 import pytest
 from pytest_mock import MockerFixture
 from starlette.exceptions import HTTPException as StarletteHTTPException
@@ -146,6 +147,46 @@ def exception_handler(request: Request, exc: Exception) -> Response:
         }
 
 
+def test_exception_handler_middleware_handler_response_type_encoding(
+    scope: HTTPScope, middleware: ExceptionHandlerMiddleware
+) -> None:
+    class ErrorMessage(pydantic.BaseModel):
+        message: str
+
+    @get("/")
+    def handler(_: Request) -> None:
+        raise Exception
+
+    def exception_handler(_: Request, _e: Exception) -> Response:
+        return Response(content=ErrorMessage(message="the error message"), status_code=HTTP_500_INTERNAL_SERVER_ERROR)
+
+    app = Litestar(route_handlers=[handler], exception_handlers={Exception: exception_handler}, openapi_config=None)
+
+    with TestClient(app) as client:
+        response = client.get("/")
+        assert response.json() == {"message": "the error message"}
+
+
+def test_exception_handler_middleware_handler_response_type_encoding_no_route_handler(
+    scope: HTTPScope, middleware: ExceptionHandlerMiddleware
+) -> None:
+    class ErrorMessage(pydantic.BaseModel):
+        message: str
+
+    @get("/")
+    def handler(_: Request) -> None:
+        raise Exception
+
+    def exception_handler(_: Request, _e: Exception) -> Response:
+        return Response(content=ErrorMessage(message="the error message"), status_code=HTTP_500_INTERNAL_SERVER_ERROR)
+
+    app = Litestar(route_handlers=[handler], exception_handlers={Exception: exception_handler}, openapi_config=None)
+
+    with TestClient(app) as client:
+        response = client.get("/not-found")
+        assert response.json() == {"message": "the error message"}
+
+
 def test_exception_handler_middleware_calls_app_level_after_exception_hook() -> None:
     @get("/test")
     def handler() -> None: