Update the handling of CORS 500 status code (#789)

Author: wu-clan

backend/common/exception/exception_handler.py

@@ -4,7 +4,6 @@
 from fastapi.exceptions import RequestValidationError
 from pydantic import ValidationError
 from starlette.exceptions import HTTPException
-from starlette.middleware.cors import CORSMiddleware
 from uvicorn.protocols.http.h11_impl import STATUS_PHRASES
 
 from backend.common.exception.errors import BaseExceptionMixin
@@ -193,66 +192,8 @@ async def all_unknown_exception_handler(request: Request, exc: Exception):
         else:
             res = response_base.fail(res=CustomResponseCode.HTTP_500)
             content = res.model_dump()
-        request.state.__request_all_unknown_exception__ = content
         content.update(trace_id=get_request_trace_id(request))
         return MsgSpecJSONResponse(
             status_code=StandardResponseCode.HTTP_500,
             content=content,
         )
-
-    if settings.MIDDLEWARE_CORS:
-
-        @app.exception_handler(StandardResponseCode.HTTP_500)
-        async def cors_custom_code_500_exception_handler(request, exc):
-            """
-            跨域自定义 500 异常处理
-
-            `Related issue <https://github.com/encode/starlette/issues/1175>`_
-
-            `Solution <https://github.com/fastapi/fastapi/discussions/7847#discussioncomment-5144709>`_
-
-            :param request: FastAPI 请求对象
-            :param exc: 自定义异常
-            :return:
-            """
-            if isinstance(exc, BaseExceptionMixin):
-                content = {
-                    'code': exc.code,
-                    'msg': exc.msg,
-                    'data': exc.data,
-                }
-            else:
-                if settings.ENVIRONMENT == 'dev':
-                    content = {
-                        'code': StandardResponseCode.HTTP_500,
-                        'msg': str(exc),
-                        'data': None,
-                    }
-                else:
-                    res = response_base.fail(res=CustomResponseCode.HTTP_500)
-                    content = res.model_dump()
-            request.state.__request_cors_500_exception__ = content
-            content.update(trace_id=get_request_trace_id(request))
-            response = MsgSpecJSONResponse(
-                status_code=exc.code if isinstance(exc, BaseExceptionMixin) else StandardResponseCode.HTTP_500,
-                content=content,
-                background=exc.background if isinstance(exc, BaseExceptionMixin) else None,
-            )
-            origin = request.headers.get('origin')
-            if origin:
-                cors = CORSMiddleware(
-                    app=app,
-                    allow_origins=settings.CORS_ALLOWED_ORIGINS,
-                    allow_credentials=True,
-                    allow_methods=['*'],
-                    allow_headers=['*'],
-                    expose_headers=settings.CORS_EXPOSE_HEADERS,
-                )
-                response.headers.update(cors.simple_headers)
-                has_cookie = 'cookie' in request.headers
-                if cors.allow_all_origins and has_cookie:
-                    response.headers['Access-Control-Allow-Origin'] = origin
-                elif not cors.allow_all_origins and cors.is_allowed_origin(origin=origin):
-                    response.headers['Access-Control-Allow-Origin'] = origin
-                    response.headers.add_vary_header('Origin')
-            return response

backend/core/registrar.py

@@ -13,7 +13,9 @@
 from fastapi_limiter import FastAPILimiter
 from fastapi_pagination import add_pagination
 from starlette.middleware.authentication import AuthenticationMiddleware
+from starlette.middleware.cors import CORSMiddleware
 from starlette.staticfiles import StaticFiles
+from starlette.types import ASGIApp
 
 from backend.common.exception.exception_handler import register_exception
 from backend.common.log import set_custom_logfile, setup_logging
@@ -65,7 +67,23 @@ async def register_init(app: FastAPI) -> AsyncGenerator[None, None]:
 
 def register_app() -> FastAPI:
     """注册 FastAPI 应用"""
-    app = FastAPI(
+
+    class MyFastAPI(FastAPI):
+        if settings.MIDDLEWARE_CORS:
+            # Related issues
+            # https://github.com/fastapi/fastapi/discussions/7847
+            # https://github.com/fastapi/fastapi/discussions/8027
+            def build_middleware_stack(self) -> ASGIApp:
+                return CORSMiddleware(
+                    super().build_middleware_stack(),
+                    allow_origins=settings.CORS_ALLOWED_ORIGINS,
+                    allow_credentials=True,
+                    allow_methods=['*'],
+                    allow_headers=['*'],
+                    expose_headers=settings.CORS_EXPOSE_HEADERS,
+                )
+
+    app = MyFastAPI(
         title=settings.FASTAPI_TITLE,
         version=settings.FASTAPI_VERSION,
         description=settings.FASTAPI_DESCRIPTION,
@@ -134,19 +152,6 @@ def register_middleware(app: FastAPI) -> None:
     # I18n
     app.add_middleware(I18nMiddleware)
 
-    # CORS
-    if settings.MIDDLEWARE_CORS:
-        from fastapi.middleware.cors import CORSMiddleware
-
-        app.add_middleware(
-            CORSMiddleware,
-            allow_origins=settings.CORS_ALLOWED_ORIGINS,
-            allow_credentials=True,
-            allow_methods=['*'],
-            allow_headers=['*'],
-            expose_headers=settings.CORS_EXPOSE_HEADERS,
-        )
-
     # Access log
     app.add_middleware(AccessMiddleware)