public async Task <IActionResult> Borrar(CambiarRolViewModel model)
        {
            var user = _userManager.Users.FirstOrDefault(u => u.UserName == model.UserName);

            if (user != null)
            {
                await _userManager.DeleteAsync(user);
            }

            return(RedirectToAction("Usuarios"));
        }
        public async Task <IActionResult> Borrar(string id)
        {
            var user = _userManager.Users.FirstOrDefault(u => u.UserName == id);

            var roles = await _userManager.GetRolesAsync(user);

            var model = new CambiarRolViewModel()
            {
                UserName = user.UserName,
                Email    = user.Email,
                Roles    = string.Join(",", roles)
            };

            return(View(model));
        }
        public async Task <IActionResult> Roles(CambiarRolViewModel model)
        {
            var user  = _userManager.Users.FirstOrDefault(u => u.UserName == model.UserName);
            var roles = await _userManager.GetRolesAsync(user);

            //Quitar los roles anteriores
            await _userManager.RemoveFromRolesAsync(user, roles);



            //   if(!roles.Contains(model.Roles)){
            if (!string.IsNullOrWhiteSpace(model.Roles))
            {
                await _userManager.AddToRoleAsync(user, model.Roles);
            }

            // }else{
            //No se hace nada.
            // }

            return(RedirectToAction("Usuarios"));
        }