Struts 2 ModelDriven Action suporting both a list and individual items - rest

Question

I have inherited some struts2 REST-plugin based code, and the following construct puzzles me:
#Namespace("/merchants/{id}")
public class MerchantAction extends ActionSupport implements ModelDriven<Object> {
private Merchant merchant = new Merchant(); // A Model
private Iterable<Merchant> merchants; // A list of models
....
public HttpHeaders index() {
merchants = merchantService.findAllMerchants();
return new DefaultHttpHeaders("index");
}
#Override
public Object getModel() {
return (merchant != null ? merchant : merchants);
}
public void setId(String id) {
merchant = merchantService.findMerchant(id));
}
In other words, it seems to be toggling between returning a list and returning an individual item in the getModel() call. Is this kosher ? Looks a bit strange to me

Answer 1

I've considered your approach, but finally gave it up. IMO, it lost the advantage of strong typed action.
My solution is, creating a ViewModel for each action. In the view models, there can be the single model, the list of the model, and other items for pages usage, such as items for drop down list or radio buttons.
So the UserViewModel is like:
public class UserViewModel implements IViewModel<User> {
private User model;
private List<User> list;
public void setModel(User user) {
this.model = user;
}
public User getModel() {
return model;
}
public void setList(List<User> list) {
this.list = list;
}
public List<User> getList() {
return list;
}
}
And the actions are like:
public class UserController implements ModelDriven<UserViewModel> {
private int id;
private UserViewModel model = new UserViewModel();
public String index() {
return "success";
}
public String show() {
return "success";
}
public void setId(int id) {
this.id = id;
}
public int getId() {
return this.id;
}
#Override
public UserViewModel getModel() {
return model;
}
}
But in this way, I still lose the shortcut way in jsp files. I should write long model.userName instead of short userName.
I'm still finding the best solution of it.