Property binding vs model-driven binding

This note helps explain how Struts2 turns request parameters into action state. It works well alongside the user form and validation examples.

Property-driven

• Define simple fields directly on the action.
• Expose setters and getters for each form field.
• Great for short demos and small forms.

Model-driven

• Return a dedicated model object from getModel().
• Keep request data separate from action orchestration logic.
• Better for larger forms and nested objects.

public class UserAction extends ActionSupport implements ModelDriven<User> {
    private final User user = new User();

    @Override
    public User getModel() {
        return user;
    }
}