public async Task <IActionResult> Create([Bind("UserDataForeignKey,GroupForeignKey")] UserDataGroup userDataGroup)
        {
            if (ModelState.IsValid)
            {
                _context.Add(userDataGroup);
                await _context.SaveChangesAsync();

                return(RedirectToAction(nameof(Index)));
            }
            ViewData["GroupForeignKey"]    = new SelectList(_context.groups, "GroupId", "GroupId", userDataGroup.GroupForeignKey);
            ViewData["UserDataForeignKey"] = new SelectList(_context.users, "UserDataId", "UserDataId", userDataGroup.UserDataForeignKey);
            return(View(userDataGroup));
        }