public IActionResult ByUser(int?id)
        {
            if (!id.HasValue)
            {
                return(RedirectToAction("Index"));
            }

            var user  = _usersService.GetFirstUserById(id.Value);
            var posts = _postsService.GetAllPostsByUserId(id.Value);

            var model = new PostsByUserViewModel
            {
                User  = user,
                Posts = posts
            };

            return(View());
        }
        public IActionResult Details(int?id)
        {
            if (!id.HasValue)
            {
                return(RedirectToAction("Index"));
            }

            var user  = _usersService.GetFirstUserById(id.Value);
            var posts = _postsService.GetAllPostsByUserId(id.Value);

            user.Posts = posts;

            var model = new UsersDetailsViewModel
            {
                User = user
            };

            return(View(model));
        }