更新条目时出错。有关详细信息，请参阅内部异常。 - Asps.net MVC 3

Question

每次我运行并尝试创建帖子时都会出现此异常..

我有一个简单的用户、帖子、评论、标签实体。它具有我定义的关系关联。当我检查 innerException 时，它说 "Cannot insert the value NULL into column 'CommentID', table " ... 并指向我定义了关系的上下文..请检查我的关系并帮助我找到我声明在评论 ID 中不允许 null 的地方...

1. 1 个用户可以有很多帖子，可以创建很多标签，可以有很多 厘米
2. 1 个帖子可以有 1 个用户，多个 cmets，并且可以有多个标签
3. 1 个标签可以有 1 个用户，多个帖子
4. 1 条评论可以有 1 个用户，1 个帖子

关系...

modelBuilder.Entity<User>().HasMany(p => p.Posts).WithRequired(u => u.Users).HasForeignKey(P=>P.UserID);
            modelBuilder.Entity<User>().HasMany(t => t.Tags).WithRequired(u => u.Users);
            modelBuilder.Entity<User>().HasMany(c => c.Comments).WithRequired(u => u.Users);

            modelBuilder.Entity<Post>().HasRequired(u => u.Users).WithMany(p=>p.Posts);
            modelBuilder.Entity<Post>().HasMany(t => t.Tags).WithMany(p => p.Posts);
            modelBuilder.Entity<Post>().HasOptional(c => c.Comments);


            modelBuilder.Entity<Comment>().HasRequired(u => u.Users);
            modelBuilder.Entity<Comment>().HasRequired(p => p.Posts);

            modelBuilder.Entity<Tag>().HasRequired(u => u.Users);
            modelBuilder.Entity<Tag>().HasMany(p => p.Posts).WithMany(t => t.Tags);

模型 - 用户

[ScaffoldColumn(true)]
        [Key]
        public int UserID { get; set; }

        [StringLength(15)]
        [DisplayName("First Name")]
        [Required(ErrorMessage="First Name is Required")]
        public string FirstName { get; set; }

        [StringLength(15)]
        [DisplayName("Last Name")]
        [Required(ErrorMessage = "Last Name is Required")]
        public string LastName { get; set; }

        [DataType(DataType.EmailAddress,ErrorMessage="please enter valid email")]
        [DisplayName("Email Address")]
        [Required(ErrorMessage = "Email is Required")]
        [Remote("CheckUniqueEmail","User",ErrorMessage="An account with this email address already exists.")]
        public string Email { get; set; }

        [DataType(DataType.Password)]
        [Required(ErrorMessage = "Password is Required")]
        public string Password { get; set; }

        [DataType(DataType.Date)]
        [ScaffoldColumn(true)]
        public DateTime JoiningDate { get; set; }

        [DataType(DataType.Date)]
        [ScaffoldColumn(true)]
        public DateTime? LastActivityDate { get; set; }

        public virtual ICollection<Post> Posts { get; set; }

        public virtual ICollection<Comment> Comments { get; set; }

        public virtual ICollection<Tag> Tags { get; set; }

模型 - 帖子

[Key]
        [ScaffoldColumn(true)]
        public int PostID { get; set; }

        [Required(ErrorMessage="Required")]
        [StringLength(250)]
        public string Title { get; set; }

        [Required(ErrorMessage="Required")]
        [DataType(DataType.MultilineText)]
        public string Body { get; set; }

        [DataType(DataType.Date)]
        public DateTime DateCreated { get; set; }

        [DataType(DataType.Date)]
        public DateTime DateModified { get; set; }

        [ScaffoldColumn(false)]
        public int UserID { get; set; }

        [ScaffoldColumn(false)]
        public int? CommentID { get; set; }

        [ScaffoldColumn(false)]
        public int? TagID { get; set; }

        public virtual ICollection<Comment> Comments { get; set; }

        public virtual User Users { get; set; }

        public virtual ICollection<Tag> Tags { get; set; }

模型 = 评论

[Key]
        [ScaffoldColumn(true)]
        public int CommentID { get; set; }

        [DisplayName("Your Comment")]
        public string Body { get; set; }

        [DataType(DataType.Date)]
        [ScaffoldColumn(true)]
        public DateTime DateCreated { get; set; }

        [ScaffoldColumn(true)]
        public int PostID { get; set; }

        [ScaffoldColumn(true)]
        public int UserID { get; set; }

        public User User { get; set; }

        public Post Posts { get; set; }

模型 = 标记

[Key]
        [ScaffoldColumn(true)]
        public int TagID { get; set; }

        [StringLength(15)]
        public string Name { get; set; }

        [ScaffoldColumn(true)]
        public int UserID { get; set; }

        public User Users { get; set; }

        public ICollection<Post> Posts { get; set; }

Answer 1

您需要在此处发布您的模型以了解更多详细信息。但我可以看到您的模型配置存在几个问题。 正如你所说，

1 comment can have 1 user, 1 post

那么在Comment 中收集用户有什么意义

modelBuilder.Entity<Comment>().HasRequired(u => u.Users); 

应该是这样的

 modelBuilder.Entity<Comment>().HasRequired(u => u.User);

这也适用于Post。