Fix ObjectId serialization with comprehensive recursive conversion - Handle all ObjectId fields in nested structures and datetime objects

app.py

@@ -305,27 +305,27 @@ def serialize_checklist(checklist_doc: Dict[str, Any]) -> Dict[str, Any]:
         Dictionary with ObjectId converted to string
     """
     import copy
+    import json
+    from bson import ObjectId
     
     # Make a deep copy to avoid modifying the original document
     serialized = copy.deepcopy(checklist_doc)
     
-    if serialized and '_id' in serialized:
-        serialized['_id'] = str(serialized['_id'])
-    
-    # Convert datetime objects to ISO strings
-    for field in ['createdAt', 'updatedAt', 'verificationDate']:
-        if field in serialized and serialized[field]:
-            # Only convert if it's a datetime object, not a string
-            if hasattr(serialized[field], 'isoformat'):
-                serialized[field] = serialized[field].isoformat()
+    # Convert ObjectId to string recursively
+    def convert_objectid(obj):
+        if isinstance(obj, ObjectId):
+            return str(obj)
+        elif isinstance(obj, dict):
+            return {key: convert_objectid(value) for key, value in obj.items()}
+        elif isinstance(obj, list):
+            return [convert_objectid(item) for item in obj]
+        elif hasattr(obj, 'isoformat'):  # datetime objects
+            return obj.isoformat()
+        else:
+            return obj
     
-    # Convert datetime objects in items
-    for section in serialized.get('sections', []):
-        for item in section.get('items', []):
-            if 'checkedAt' in item and item['checkedAt']:
-                # Only convert if it's a datetime object, not a string
-                if hasattr(item['checkedAt'], 'isoformat'):
-                    item['checkedAt'] = item['checkedAt'].isoformat()
+    # Apply ObjectId conversion to the entire document
+    serialized = convert_objectid(serialized)
     
     return serialized