1 Building a Minimal Front-End Web App in Seven Steps Run the app Get the code 2 Adding Constraint Validation Run the app Get the code 3 Dealing with Enumerations Run the app Get the code 4 Managing Unidirectional Associations Run the app Get the code 5 Managing Bidirectional Associations Run the app Get the code 6 Handling Subtype Relationships in Class Hierarchies Run the app Get the code Back to top View the discussion thread.