MVC2 ListBox not binding from View to Controller

Question

I have a many-to-many relationship in NHibernate, and I'm trying to bind all items in a Html.ListBoxFor() to my Model, but that list always comes with 0 items in the Model passed to Controller.

Here's what I've got so far:

Role.hbm.xml > 'left' side of many-to-many relationship

<bag name="LdapGroups" table="CADU_TB_ROLE_LDAP_OBJECTS" cascade="all">
    <key column="ID_ROLE" />
    <many-to-many  column="ID_LDAP_OBJECT" class="LdapObject" />
</bag>

Role.cs > Model

public class Role {
    public virtual IList<LdapObjects> LdapGroups {
        get;
        set;
    }
}

RoleController.cs > Controller

public class RoleController: Controller {
    public ActionResult Create(Role obj) {
        // Create logic here
        // here, obj.LdapGroups.Count is equal to 0, but instantiated
    }
}

Create.aspx > View (right list in image below)

<%= Html.ListBoxFor(model => model.LdapGroups,
    new List<CaduMVC.Models.LdapObject>()
        .Select(o => new SelectListItem() {
            Value = o.Id.ToString(),
            Text = o.Description
        }),
        new { id="lbSelectedGroups",
              @class = "form-control",
              style = "height: 120px;" }) %>

Here's the View (Items are passed from left to right using JQuery. Item type is LdapObject)

I need to get all items from lbSelectedGroups (right list) and put them in the obj (obj.LdapGroups) param (Create Action), but it comes with 0 items

How can I do that?

Answer 1

After some debugging, I found that Html.ListBoxFor() method sends a collection of values ​​(value attribute from option tag), and not the ListItem objects (which I was expecting). I created a transient property in the Model object of type int[], which receives that list of values, then create and insert the deattached objects into the list of LdapObjects. As follows:

Role.cs > Model

public class Role {
    public virtual IList<LdapObjects> LdapGroups {
        get;
        set;
    }
    // Transient
    public virtual int[] LdapGroupsSelected {
        get;
        set;
    }
}

Create.aspx > View (right list in image above)

<%= Html.ListBoxFor(model => model.GruposLdapSelecionados,
    new Iesi.Collections.Generic.HashedSet<CaduMVC.Models
            .LdapObject>()
        .Select(o => new SelectListItem() {
            Value = o.Id.ToString(),
            Text = o.Descricao,
        }),
        new { id="lbGruposSelecionados",
            @class = "form-control",
            style = "height: 120px;" }) %>

RoleController.cs > Controller

public ActionResult Create(Role obj) {
    . . .
    for(int i = 0; i < obj.LdapGroupsSelected.Length; i++) {
        obj.LdapGroups.Add(new LdapObject(Convert.ToInt32(
                obj.LdapGroupsSelected[i])));
    }
    session.Merge(obj);
}

Answer 2

At a first glance what i see is there is controller action missing when click on >> button. That action should get all items in the both lists via jquery get using a pattern and pass a collection of items to controller. The action will push items to second box and send the result. The jquery success method take data from collections and refill both List Boxes.