I'm a newbie and I have the following problem:

I have three classes:

Class1 {
String id;
Class2 c2;
Class3 c3;
... getters and setters...
}

Class2 {
String id;
String description;
}

Class3 {
String id;
String description;
}


and I have to use a form to create/modify Class1 instances, using as input a List of Class2 instances and a list of Class3 instances.

That is, I want the user choose a Class2 instance from a select, and a Class32 instance from another select, to create a Class1 instance and save it to the database. I want to do validation on these choices.

I'm using a SimpleFormController as controller, but don't know what are the best methods to override to put the lists into the model (referenceData or formBackingObject or ???).

I suppose I have to use <spring:transform>, but I really haven't understood it.

Any help would be really appreciated (I'd like to have snippets of the controller, the jsp page, etc...)

Thanks,
Luigi