Refactor request body validation using decorator

backend/models/dtos/__init__.py

@@ -0,0 +1,33 @@
+from functools import wraps
+from flask import request
+from schematics.exceptions import DataError
+
+
+from backend.exceptions import BadRequest
+
+
+def get_validation_errors(e):
+    """Returns a list of validation errors from a schematics DataError"""
+    return [
+        {"field": field, "message": str(error[0])} for field, error in e.errors.items()
+    ]
+
+
+def validate_request_body(dto_class):
+    """Decorator to validate request body against a DTO class"""
+
+    def decorator(f):
+        @wraps(f)
+        def wrapper(*args, **kwargs):
+            try:
+                dto = dto_class(request.get_json())
+                dto.validate()
+                request.validated_dto = dto
+            except DataError as e:
+                field_errors = get_validation_errors(e)
+                raise BadRequest(field_errors=field_errors)
+            return f(*args, **kwargs)
+
+        return wrapper
+
+    return decorator