feat: add optional data field in ApiError (#63)

src/fastapi_toolsets/exceptions/exceptions.py

@@ -183,7 +183,7 @@ def generate_error_responses(
             "content": {
                 "application/json": {
                     "example": {
-                        "data": None,
+                        "data": api_error.data,
                         "status": ResponseStatus.FAIL.value,
                         "message": api_error.msg,
                         "description": api_error.desc,

src/fastapi_toolsets/exceptions/handler.py

@@ -7,7 +7,7 @@ from fastapi.exceptions import RequestValidationError, ResponseValidationError
 from fastapi.openapi.utils import get_openapi
 from fastapi.responses import JSONResponse
 
-from ..schemas import ResponseStatus
+from ..schemas import ErrorResponse, ResponseStatus
 from .exceptions import ApiException
 
 
@@ -54,16 +54,16 @@ def _register_exception_handlers(app: FastAPI) -> None:
     async def api_exception_handler(request: Request, exc: ApiException) -> Response:
         """Handle custom API exceptions with structured response."""
         api_error = exc.api_error
+        error_response = ErrorResponse(
+            data=api_error.data,
+            message=api_error.msg,
+            description=api_error.desc,
+            error_code=api_error.err_code,
+        )
 
         return JSONResponse(
             status_code=api_error.code,
-            content={
-                "data": None,
-                "status": ResponseStatus.FAIL.value,
-                "message": api_error.msg,
-                "description": api_error.desc,
-                "error_code": api_error.err_code,
-            },
+            content=error_response.model_dump(),
         )
 
     @app.exception_handler(RequestValidationError)
@@ -83,15 +83,15 @@ def _register_exception_handlers(app: FastAPI) -> None:
     @app.exception_handler(Exception)
     async def generic_exception_handler(request: Request, exc: Exception) -> Response:
         """Handle all unhandled exceptions with a generic 500 response."""
+        error_response = ErrorResponse(
+            message="Internal Server Error",
+            description="An unexpected error occurred. Please try again later.",
+            error_code="SERVER-500",
+        )
+
         return JSONResponse(
             status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
-            content={
-                "data": None,
-                "status": ResponseStatus.FAIL.value,
-                "message": "Internal Server Error",
-                "description": "An unexpected error occurred. Please try again later.",
-                "error_code": "SERVER-500",
-            },
+            content=error_response.model_dump(),
         )
 
 
@@ -116,15 +116,16 @@ def _format_validation_error(
             }
         )
 
+    error_response = ErrorResponse(
+        data={"errors": formatted_errors},
+        message="Validation Error",
+        description=f"{len(formatted_errors)} validation error(s) detected",
+        error_code="VAL-422",
+    )
+
     return JSONResponse(
         status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
-        content={
-            "data": {"errors": formatted_errors},
-            "status": ResponseStatus.FAIL.value,
-            "message": "Validation Error",
-            "description": f"{len(formatted_errors)} validation error(s) detected",
-            "error_code": "VAL-422",
-        },
+        content=error_response.model_dump(),
     )
 
 

src/fastapi_toolsets/schemas.py

@@ -1,7 +1,7 @@
 """Base Pydantic schemas for API responses."""
 
 from enum import Enum
-from typing import ClassVar, Generic, TypeVar
+from typing import Any, ClassVar, Generic, TypeVar
 
 from pydantic import BaseModel, ConfigDict
 
@@ -50,6 +50,7 @@ class ApiError(PydanticBase):
     msg: str
     desc: str
     err_code: str
+    data: Any | None = None
 
 
 class BaseResponse(PydanticBase):
@@ -84,7 +85,7 @@ class ErrorResponse(BaseResponse):
 
     status: ResponseStatus = ResponseStatus.FAIL
     description: str | None = None
-    data: None = None
+    data: Any | None = None
 
 
 class Pagination(PydanticBase):

tests/test_exceptions.py

@@ -108,6 +108,24 @@ class TestGenerateErrorResponses:
         assert example["status"] == "FAIL"
         assert example["error_code"] == "RES-404"
         assert example["message"] == "Not Found"
+        assert example["data"] is None
+
+    def test_response_example_with_data(self):
+        """Generated response includes data when set on ApiError."""
+
+        class ErrorWithData(ApiException):
+            api_error = ApiError(
+                code=400,
+                msg="Bad Request",
+                desc="Invalid input.",
+                err_code="BAD-400",
+                data={"details": "some context"},
+            )
+
+        responses = generate_error_responses(ErrorWithData)
+        example = responses[400]["content"]["application/json"]["example"]
+
+        assert example["data"] == {"details": "some context"}
 
 
 class TestInitExceptionsHandlers:
@@ -137,6 +155,59 @@ class TestInitExceptionsHandlers:
         assert data["error_code"] == "RES-404"
         assert data["message"] == "Not Found"
 
+    def test_handles_api_exception_without_data(self):
+        """ApiException without data returns null data field."""
+        app = FastAPI()
+        init_exceptions_handlers(app)
+
+        @app.get("/error")
+        async def raise_error():
+            raise NotFoundError()
+
+        client = TestClient(app)
+        response = client.get("/error")
+
+        assert response.status_code == 404
+        assert response.json()["data"] is None
+
+    def test_handles_api_exception_with_data(self):
+        """ApiException with data returns the data payload."""
+        app = FastAPI()
+        init_exceptions_handlers(app)
+
+        class CustomValidationError(ApiException):
+            api_error = ApiError(
+                code=422,
+                msg="Validation Error",
+                desc="1 validation error(s) detected",
+                err_code="CUSTOM-422",
+                data={
+                    "errors": [
+                        {
+                            "field": "email",
+                            "message": "invalid format",
+                            "type": "value_error",
+                        }
+                    ]
+                },
+            )
+
+        @app.get("/error")
+        async def raise_error():
+            raise CustomValidationError()
+
+        client = TestClient(app)
+        response = client.get("/error")
+
+        assert response.status_code == 422
+        data = response.json()
+        assert data["data"] == {
+            "errors": [
+                {"field": "email", "message": "invalid format", "type": "value_error"}
+            ]
+        }
+        assert data["error_code"] == "CUSTOM-422"
+
     def test_handles_validation_error(self):
         """Handles validation errors with structured response."""
         from pydantic import BaseModel

tests/test_schemas.py

@@ -46,6 +46,31 @@ class TestApiError:
         assert error.desc == "The resource was not found."
         assert error.err_code == "RES-404"
 
+    def test_data_defaults_to_none(self):
+        """ApiError data field defaults to None."""
+        error = ApiError(
+            code=404,
+            msg="Not Found",
+            desc="The resource was not found.",
+            err_code="RES-404",
+        )
+        assert error.data is None
+
+    def test_create_with_data(self):
+        """ApiError can be created with a data payload."""
+        error = ApiError(
+            code=422,
+            msg="Validation Error",
+            desc="2 validation error(s) detected",
+            err_code="VAL-422",
+            data={
+                "errors": [{"field": "name", "message": "required", "type": "missing"}]
+            },
+        )
+        assert error.data == {
+            "errors": [{"field": "name", "message": "required", "type": "missing"}]
+        }
+
     def test_requires_all_fields(self):
         """ApiError requires all fields."""
         with pytest.raises(ValidationError):