Initial commit

skills/api-design-standards/templates/error-handler.py

@@ -0,0 +1,115 @@
+# Grey Haven Studio - Error Handler Template
+# Add this to app/core/exceptions.py
+
+from fastapi import HTTPException, Request, status
+from fastapi.responses import JSONResponse
+from fastapi.exceptions import RequestValidationError
+from sqlalchemy.exc import IntegrityError, OperationalError
+import logging
+
+logger = logging.getLogger(__name__)
+
+
+async def http_exception_handler(request: Request, exc: HTTPException) -> JSONResponse:
+    """Handle HTTPException with standard error format."""
+    logger.warning(f"HTTP exception: {exc.status_code} - {exc.detail}")
+
+    return JSONResponse(
+        status_code=exc.status_code,
+        content={
+            "error": exc.detail,
+            "status_code": exc.status_code,
+        },
+        headers=exc.headers,
+    )
+
+
+async def validation_exception_handler(
+    request: Request, exc: RequestValidationError
+) -> JSONResponse:
+    """Handle Pydantic validation errors."""
+    errors = []
+    for error in exc.errors():
+        field_path = ".".join(str(loc) for loc in error["loc"] if loc != "body")
+        errors.append(
+            {
+                "field": field_path if field_path else None,
+                "message": error["msg"],
+                "code": error["type"],
+            }
+        )
+
+    logger.warning(f"Validation error: {errors}")
+
+    return JSONResponse(
+        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+        content={
+            "error": "Validation error",
+            "detail": errors,
+            "status_code": 422,
+        },
+    )
+
+
+async def integrity_error_handler(
+    request: Request, exc: IntegrityError
+) -> JSONResponse:
+    """Handle database integrity errors."""
+    logger.error(f"Integrity error: {exc}")
+
+    error_detail = "A resource with this unique value already exists"
+    if "foreign key" in str(exc).lower():
+        error_detail = "Referenced resource does not exist"
+
+    return JSONResponse(
+        status_code=status.HTTP_409_CONFLICT,
+        content={
+            "error": error_detail,
+            "status_code": 409,
+        },
+    )
+
+
+async def operational_error_handler(
+    request: Request, exc: OperationalError
+) -> JSONResponse:
+    """Handle database operational errors."""
+    logger.error(f"Database operational error: {exc}")
+
+    return JSONResponse(
+        status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
+        content={
+            "error": "Service temporarily unavailable",
+            "detail": "Database connection error. Please try again later.",
+            "status_code": 503,
+        },
+    )
+
+
+async def generic_exception_handler(request: Request, exc: Exception) -> JSONResponse:
+    """Catch-all handler for unexpected exceptions."""
+    logger.exception(f"Unhandled exception: {exc}")
+
+    return JSONResponse(
+        status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
+        content={
+            "error": "Internal server error",
+            "status_code": 500,
+        },
+    )
+
+
+# Register in main.py:
+# from app.core.exceptions import (
+#     http_exception_handler,
+#     validation_exception_handler,
+#     integrity_error_handler,
+#     operational_error_handler,
+#     generic_exception_handler,
+# )
+#
+# app.add_exception_handler(HTTPException, http_exception_handler)
+# app.add_exception_handler(RequestValidationError, validation_exception_handler)
+# app.add_exception_handler(IntegrityError, integrity_error_handler)
+# app.add_exception_handler(OperationalError, operational_error_handler)
+# app.add_exception_handler(Exception, generic_exception_handler)