public ActionResult ChangeRole(ChangeRoleViewModel model)
 {
     var user = UserManager.FindByName(model.Nickname);
     if (ModelState.IsValid && user != null)
     {
         if (model.Admin)
             UserManager.AddToRole(user.Id, "Admin");
         else if (UserManager.IsInRole(user.Id, "Admin"))
             UserManager.RemoveFromRole(user.Id, "Admin");
         if (model.Modo)
             UserManager.AddToRole(user.Id, "Moderator");
         else if (UserManager.IsInRole(user.Id, "Moderator"))
             UserManager.RemoveFromRole(user.Id, "Moderator");
         return RedirectToAction("Display", "Account", new { nickname = model.Nickname });
     }
     return View(model);
 }
 public ActionResult ChangeRole(string nickname)
 {
     var user = Engine.BusinessManagement.User.FindUserByNickname(nickname);
     var model = new ChangeRoleViewModel()
         {
             Nickname = nickname,
             Admin = user.Roles.Find(role => role.Value == "Admin") != null,
             Modo = user.Roles.Find(role => role.Value == "Moderator") != null,
         };
     return View(model);
 }