更新条目时发生错误。有关详细信息，请参阅内部异常 - Asps.net MVC 3

Question

我每次运行时都会遇到此异常，并尝试创建帖子..

我有一个简单的用户，帖子，评论，标签实体。有我定义的关系关联。当我检查innerException它说"Cannot insert the value NULL into column 'CommentID', table " ...并指向我的上下文，我有一个关系定义..请检查我的关系，并帮助我找到这个我已经声明，在评论ID中不允许null。

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 评论
2. 1个帖子可以有1个用户，很多评论，并且可以有很多标签
3. 1个标签可以有1个用户，很多帖子
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 - 发布

[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; }

model = Tag

[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一些问题。 正如你所说，

1 comment can have 1 user, 1 post

那么在Comment

中保持用户收集的重点是什么

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

它应该像这样

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

，这也适用于Post。