gistfile1.js

const fieldList = [
  { label: 'Foo Fields', fields: [{name: 'foo', selected: false}] },
  { label: 'Bar Fields', fields: [{name: 'bar', selected: true}] }
]

fields: Ember.computed('fieldList.@each.fields', function() {
  return this.get("fieldList").mapBy("fields");
}),

enabledFields: Ember.computed("fields", "fields.@each.selected", function(){
  return this.get("fields").filterBy("selected");
});