清空剃须刀页面，检查 cmment 中是否存在商品编号

Question

所以我有一个评论可以更新的 crud，我已经想出了如何在评论不存在时显示一条消息，但是当我放置一个不存在的文章编号时它会崩溃（文章编号不能为空）

剃刀页面背后的代码：

 public class UpdateCommentModel : PageModel
    {
        [BindProperty]
        public CommentClass comment { get; set; }
        [BindProperty]
        public int articleNumber { get; set; }

        public void OnGet()
        {
        }
        public IActionResult OnPost()
        {
            if (ModelState.IsValid)
            {
                UserManager findUser = new UserManager();
                comment.user = findUser.FindUser(Convert.ToInt32(HttpContext.Session.GetString("username")));

                NewsArticleManager FindArticleNumber = new NewsArticleManager();
                comment.article = FindArticleNumber.FindNewsArticle(articleNumber);

                CommentManager updateToCommentDatabase = new CommentManager();
                bool succeeded = updateToCommentDatabase.UpdateComment(comment);
                if (succeeded)
                {
                    string message = "The tip article has been deleted!";
                    ViewData["Message"] = message;
                }
                else
                {
                    string message = "This article does not exist";
                    ViewData["Message"] = message;
                }
                return Page();
            }
            else
            {
                ViewData["Message"] = "Please enter all data fields";
                return Page();
            }
        }

数据库代码：

 public bool UpdateDb(CommentClass comment)
        {

            using (MySqlConnection connection = new MySqlConnection(databaseConnection))
            {
                //SQL command to insert the news article into the database
                string sql = "UPDATE comment SET CommentId = @CommentId, ArticleId = @ArticleId, UserId = @UserId, CommentText = @CommentText WHERE CommentId = @CommentId AND ArticleId = ArticleId";

                MySqlCommand command = new MySqlCommand(sql, connection);
                command.Parameters.AddWithValue("@CommentId", comment.CommentId);
                command.Parameters.AddWithValue("@ArticleId", comment.article.ArticleNumber);
                command.Parameters.AddWithValue("@UserId", comment.user.UserId);
                command.Parameters.AddWithValue("@CommentText", comment.CommentText);

                connection.Open();
                int amount = command.ExecuteNonQuery();
                return amount > 0;
            }
        }

管理员代码：

//Delete article
        public bool DeleteComment(int commentId)
        {
            FillCommentList();
            return commentDB.DeleteDb(commentId);
        }

有人知道如何解决这个问题吗？

Answer 1

在不知道您的标记是什么样子的情况下，我建议：

if (articleNumber == 0)
{
    ModelState.AddError("articleNumber", "Article Number should be greater than zero");
}