Hi people, I'm facing a problem 'cause i cant bind a list with a select multiple html element.
The problem is on the submit of the form, if I select multiple elements from my html form, nothing is submited and my view is rendered another time.

I've created a custom converter: roleToSet to convert strings to set, without success:

I've defined two model class with setters and getters:

User:

Code:
@Entity
public class User implements java.io.Serializable {

    @Id
    @GeneratedValue
    private int id;
    private String name;
    @ManyToMany(cascade=CascadeType.PERSIST)
    private Set<Role> role = new HashSet<Role>(0);
and Role:

Code:
@Entity
public class Role implements java.io.Serializable {

    @Id
    private int id;
    private String name;
i've defined a flow to insert a user: createuser.xml

Code:
<?xml version="1.0" encoding="UTF-8"?>
<flow xmlns="http://www.springframework.org/schema/webflow"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.springframework.org/schema/webflow http://www.springframework.org/schema/webflow/spring-webflow-2.0.xsd">

       <persistence-context />

       <on-start>
           <evaluate expression="userManager.createUser()" result="flowScope.user" />
       </on-start>

       <view-state id="create_user" model="user" >
       <binder>
           <binding property="name" />           
           <binding property="role" converter="roleToSet"/>
       </binder>
        <on-render>
            <evaluate expression="roleManager.allRoles()" result="viewScope.rolesList" />
        </on-render>

</flow>
and the converter roleToSet:

Code:
public class roleToSet extends StringToObject {    

    public roleToSet() {
        super(Set.class);
    }   

    @Override
    protected Object toObject(String string, Class targetClass) throws Exception {
        ....        
    }

    @Override
    protected String toString(Object object) throws Exception {        
        Role role = (Role) object;
        return role.getName();
    }        
}
the problem is on my SELECT element:

Code:
<form:select path="role">
     <form:options items="${rolesList}" itemLabel="name"/>
</form:select>
If I select only one element and then i submit the form, the toObject method is called and the object will update to the database correctly.
If i select multiple elements, it doesn't submit the form, but redirects me the formView instead.

I need some help, i can't figre the problem 'cause no exception is raised