main_page.js

        filterSelect: SC.SelectFieldView.design({
            layout: {left: 20, width: 150, top: 5, height: 20},
            objects: MyApp.user.computedList(),
            nameKey: "name",
            valueKey: "guid", //changed to "value" for array
            sortKey: "name"
        }),          

user model

// doesn't work:
  computedList: function(){
    return this.get('memberships').getEach('userGroup').filterProperty('type', "myType");
    // array of SC.Objects
    // calling .toArray() has no effect on the result
  }


//works:
  computedArray: function(){
    var groups = this.get('memberships').getEach('userGroup').filterProperty('type', "myType");
    var groupsArray = new Array();
    for(var i=0; i < groups.length; i++){
      var groupsFmt = {
        name: groups.objectAt(i).get('name'),
        value: groups.objectAt(i).get('guid')
      };
      groupsArray.push(groupsFmt);
    }
    return groupsArray;
    //looks like: { name: 'MyName', value: 'MyValue' }
  }