Use an Association instead of ID
In your domain model:
Create an association → Node_RuleSet
(between Node and RuleSet).
Remove the plain string attribute storing RuleSet ID (optional).
In your page Combo Box:
Data source: RuleSet
entity (XPath or nanoflow).
Display attribute: RuleSetName
(or Name).
Value (reference): Node_RuleSet
.
In your nanoflow (when RuleSet is selected):
changeObject(NodeObj, { Node_RuleSet: selectedRuleSet });
When you reopen the page, Mendix automatically loads the associated RuleSet and displays its Name instead of ID.