fix issue with null store_id

sync/serializers.py

@@ -6,3 +6,9 @@ class DataAccessSerializer(serializers.ModelSerializer):
         model = DataAccess
         fields = '__all__'
         read_only_fields = ['user']
+
+    def to_internal_value(self, data):
+        if 'store_id' in data and data['store_id'] is None:
+            data = data.copy()  # Don't modify the original data
+            data['store_id'] = ""
+        return super().to_internal_value(data)

sync/utils.py

@@ -103,7 +103,6 @@ class HierarchyOrganizer:
         grouped = defaultdict(list)
         for instance in self.children:
             class_name = instance.__class__.__name__
-            # serializer = get_serializer(instance, class_name)
             grouped[class_name].append(instance.data_identifier_dict())
         return dict(grouped)