fix: check type of new_obj

model_diffsummary/__main__.py

@@ -241,37 +241,33 @@ def _obj2diff(
 
         old_val = getattr(old, attr)
         new_val = getattr(new, attr)
-        if isinstance(old_val, c.GenericElement):
+
+        if isinstance(old_val, c.GenericElement) and isinstance(new_val, c.GenericElement):
             if old_val.uuid != new_val.uuid:
                 changes[attr] = {
-                    "previous": {
-                        "uuid": old_val.uuid,
-                        "display_name": old_val.name,
-                    },
-                    "current": {
-                        "uuid": new_val.uuid,
-                        "display_name": new_val.name,
-                    },
+                    "previous": _serialize_obj(old_val),
+                    "current": _serialize_obj(new_val),
                 }
-        elif isinstance(old_val, c.ElementList):
+        elif isinstance(old_val, c.ElementList) and isinstance(new_val, c.ElementList):
             if [i.uuid for i in old_val] != [i.uuid for i in new_val]:
                 changes[attr] = {
-                    "previous": [
-                        {"uuid": i.uuid, "display_name": i.name}
-                        for i in old_val
-                    ],
-                    "current": [
-                        {"uuid": i.uuid, "display_name": i.name}
-                        for i in new_val
-                    ],
+                    "previous": _serialize_obj(old_val),
+                    "current": _serialize_obj(new_val),
                 }
         elif old_val != new_val:
-            changes[attr] = {"previous": old_val, "current": new_val}
+            changes[attr] = {"previous": _serialize_obj(old_val), "current": _serialize_obj(new_val)}
 
     if not changes:
         return None
     return {"uuid": old.uuid, "display_name": new.name, "changes": changes}
 
+def _serialize_obj(obj: c.GenericElement | t.Any):
+    if isinstance(obj, c.GenericElement):
+        return  {"uuid": obj.uuid,
+                 "display_name": obj.name},
+    elif isinstance(obj, c.ElementList):
+        return [{"uuid": i.uuid, "display_name": i.name} for i in obj]
+    return obj
 
 if __name__ == "__main__":
     main()