以jsp形式以Spring MVC返回子类对象

Question

How to return the subclass object to the controller from the jsp view. The page receives the proper animal list with the sub class elements. I am able to display the child class elements but when I try to send it back to the controller I am getting a binding error. This is the mock code for my issue.

   public class Group
    {
    public List<Animal> animals;
    //getters and setters 
    }


    abstract class Animal
    {
    String name;
    //getters and setters 
    }

    class Lion extends animal
    {
    String legs;
    //getters and setters 
    }

My view:

<form:hidden path="groups[${groupssList.index}].animals[${animalsList.index}].name"/>

Exception:

Could not instantiate property type [Animal] to auto-grow nested property path: java.lang.InstantiationException

Answer 1

I think your path value will result in a null reference and Spring will try populate it with a default object. To disable this default behavior, add to (each of) your @Controller class.

@InitBinder
public void initBinder(WebDataBinder binder){
    binder.setAutoGrowNestedPaths(false);
}

You will end up getting a different exception, but it will be more clear.