Struts ActionForm and Model Objects design

Question

I've managed to make a pretty nice model with persistence managed by hibernate logic encapsulated in DAO's.
But now Ive reached the web layer and I'm with struts, and I'm kind of stuck so I would love to hear some suggestions.
How should I create ActionForms without duplicating the model state in ActionForm classes?
Right now, my model implements ActionForm, which is tight coupling .
But this increases maintenability.
Other suggestions?

Answer 1

It is a very bad idea to have your model implement ActionForm, for the reason you mentioned -- tight coupling. When you do that, you are tied to a web application; and, more specifically, Struts. "Best practice" says you need to duplicate a bit of your model in your ActionForm (Jakarta Commons BeanUtils makes this painless). As you probably know, the ActionForm should correspond to the form being displayed in the browser; each HTML form element should have a corresponding property in your ActionForm class. These properties might come from various parts of your domain model, so this gives you a place to muster them all together. I use an initXXXAction to populate the ActionForm, if needed, before display and a completeXXXAction to process the users input after they submit (although I'm thinking about switching to one of the DispatchAction flavors). Also, if the idea of maintaining the ActomForm classes is a hang-up, I'd suggest looking into the DynaXXX classes.
Just to re-iterate, having your model implement ActionForm is BAD.