Merge pull request #216 from grillazz/12-add-json-field-example

refine exception handlers

Author: grillazz

app/exception_handlers.py

@@ -0,0 +1,3 @@
+from app.exception_handlers.registry import register_exception_handlers
+
+__all__ = ["register_exception_handlers"]

app/exception_handlers/__init__.py

@@ -0,0 +1,43 @@
+import orjson
+from attrs import define, field
+from fastapi import Request
+from rotoger import AppStructLogger
+
+logger = AppStructLogger().get_logger()
+
+
+@define(slots=True)
+class RequestInfo:
+    """Contains extracted request information."""
+
+    path: str = field()
+    body: dict = field(default=None)
+
+
+@define(slots=True)
+class BaseExceptionHandler:
+    """Base class for all exception handlers with common functionality."""
+
+    @staticmethod
+    async def extract_request_info(request: Request) -> RequestInfo:
+        """Extract common request information."""
+        request_path = request.url.path
+        request_body = None
+        try:
+            raw_body = await request.body()
+            if raw_body:
+                request_body = orjson.loads(raw_body)
+        except orjson.JSONDecodeError:
+            pass
+
+        return RequestInfo(path=request_path, body=request_body)
+
+    @classmethod
+    async def log_error(cls, message: str, request_info: RequestInfo, **kwargs):
+        """Log error with standardized format."""
+        await logger.aerror(
+            message,
+            request_url=request_info.path,
+            request_body=request_info.body,
+            **kwargs,
+        )

app/exception_handlers/base.py

@@ -0,0 +1,24 @@
+from fastapi import Request
+from fastapi.responses import JSONResponse
+from sqlalchemy.exc import SQLAlchemyError
+
+from app.exception_handlers.base import BaseExceptionHandler
+
+
+class SQLAlchemyExceptionHandler(BaseExceptionHandler):
+    """Handles SQLAlchemy database exceptions."""
+
+    @classmethod
+    async def handle_exception(
+        cls, request: Request, exc: SQLAlchemyError
+    ) -> JSONResponse:
+        request_info = await cls.extract_request_info(request)
+
+        await cls.log_error(
+            "Database error occurred", request_info, sql_error=repr(exc)
+        )
+
+        return JSONResponse(
+            status_code=500,
+            content={"message": "A database error occurred. Please try again later."},
+        )

app/exception_handlers/database.py

@@ -0,0 +1,16 @@
+from fastapi import FastAPI
+from fastapi.exceptions import ResponseValidationError
+from sqlalchemy.exc import SQLAlchemyError
+
+from app.exception_handlers.database import SQLAlchemyExceptionHandler
+from app.exception_handlers.validation import ResponseValidationExceptionHandler
+
+
+def register_exception_handlers(app: FastAPI) -> None:
+    """Register all exception handlers with the FastAPI app."""
+    app.add_exception_handler(
+        SQLAlchemyError, SQLAlchemyExceptionHandler.handle_exception
+    )
+    app.add_exception_handler(
+        ResponseValidationError, ResponseValidationExceptionHandler.handle_exception
+    )

app/exception_handlers/registry.py

@@ -0,0 +1,42 @@
+from fastapi import Request
+from fastapi.exceptions import ResponseValidationError
+from fastapi.responses import JSONResponse
+
+from app.exception_handlers.base import BaseExceptionHandler
+
+
+class ResponseValidationExceptionHandler(BaseExceptionHandler):
+    """Handles response validation exceptions."""
+
+    @classmethod
+    async def handle_exception(
+        cls, request: Request, exc: ResponseValidationError
+    ) -> JSONResponse:
+        request_info = await cls.extract_request_info(request)
+        errors = exc.errors()
+
+        # Check if this is a None/null response case
+        is_none_response = False
+        for error in errors:
+            if error.get("input") is None and "valid dictionary" in error.get(
+                "msg", ""
+            ):
+                is_none_response = True
+                break
+
+        await cls.log_error(
+            "Response validation error occurred",
+            request_info,
+            validation_errors=errors,
+            is_none_response=is_none_response,
+        )
+
+        if is_none_response:
+            return JSONResponse(
+                status_code=404,
+                content={"no_response": "The requested resource was not found"},
+            )
+        else:
+            return JSONResponse(
+                status_code=422, content={"response_format_error": errors}
+            )

app/exception_handlers/validation.py

@@ -25,9 +25,19 @@ async def test_add_stuff(client: AsyncClient):
             "description": stuff["description"],
         }
     )
+    response = await client.post("/stuff", json=stuff)
+    assert response.status_code == status.HTTP_500_INTERNAL_SERVER_ERROR
+    assert response.json() == snapshot(
+        {"message": "A database error occurred. Please try again later."}
+    )
 
 
 async def test_get_stuff(client: AsyncClient):
+    response = await client.get("/stuff/nonexistent")
+    assert response.status_code == status.HTTP_404_NOT_FOUND
+    assert response.json() == snapshot(
+        {"no_response": "The requested resource was not found"}
+    )
     stuff = StuffFactory.build(factory_use_constructors=True).model_dump(mode="json")
     await client.post("/stuff", json=stuff)
     name = stuff["name"]