public virtual ActionResult UserGroups(SelectUserGroupsViewModel model)
 {
     if (ModelState.IsValid)
     {
         var idManager = new IdentityManager();
         var user = _db.Users.First(u => u.UserName == model.UserName);
         idManager.ClearUserGroups(user.Id);
         foreach (var group in model.Groups)
         {
             if (group.Selected)
             {
                 idManager.AddUserToGroup(user.Id, group.GroupId);
             }
         }
         return RedirectToAction("index");
     }
     return View();
 }
 public virtual ActionResult UserGroups(string id)
 {
     var user = _db.Users.First(u => u.UserName == id);
     var model = new SelectUserGroupsViewModel(user);
     return View(model);
 }