Question

Consider a class (an ORM entity):

public class MyEntity {
    Long id;
    MyOtherEntity assoc;
    // ... getters and setters
}

I want for it to be bound automatically in a Spring MVC controller, something like that:

public ModelAndView method(HttpServletRequest request, 
    HttpServletResponse response, MyEntity command) {
}

It works well for simple properties like id, but for assoc it throws an exception NullValueInNestedPathException, since assoc wasn’t instantiated by constructor. The question is, how can I tell ServletRequestDataBinder (or BeanWrapper or anything) to instantiate properties automatically as it makes its way through the nested property path?

I could of course make another class derived from MyEntity and put an instantiation in it, but then I won’t be able to save it using simple Hibernate call, since derived class won’t be mapped.

Answer 1

Ok, one way to do that in case of MultiActionController is to override newCommandObject; but I would like a more generic solution.