Introducing FOREIGN KEY constraint 'FK_dbo.Votes_dbo.Nodes_NodesId' on table 'Votes' may cause cycles or multiple cascade paths

Hi all,i'm trying to create database using code first.I'm using aspnet web api 2,ef 6 andvs studio 2013.These are my classes :

public class Comment
    {
        
        public virtual int CommentId { get; set; }
        public virtual string Content { get; set; }
        public virtual int? LikesCount { get; set; }
        public virtual Int64? Created { get; set; }
        public virtual int NodesId { get; set; }
        public virtual string UsersId { get; set; }
        public ICollection<Votes> Votes { get; set; }
        public Nodes Nodes { get; set; }
        public ApplicationUsers Users { get; set; }
    }

public class Nodes
    {
        public virtual int NodesId { get; set; }
        public virtual string Type { get; set; }
        public virtual string Subject { get; set; }
        public virtual string Content { get; set; }
        public virtual int? GroupsId { get; set; }
        public virtual int? LikesCount { get; set; }
        public virtual Int64? Created { get; set; }
        public virtual Int64? Edited { get; set; }
        public virtual string UsersId { get; set; }
        //public virtual int UsersId { get; set; }
        public Groups Groups { get; set; }
        public ApplicationUsers Users { get; set; }
        public ICollection<Votes> Votes { get; set; }
    }

public class Votes
    {   
        public virtual int Id { get; set; }
        public virtual int NodesId { get; set; }
        public Nodes Nodes { get; set; }
        public virtual int CommentId { get; set; }
        public Comment Comment { get; set; }
        public virtual string UsersId { get; set; }
        public ApplicationUsers Users { get; set; }   
    }

public class ApplicationUsers : IdentityUser
    {
        public virtual string Email { get; set; }
       
        public int FriendId { get; set; }

        public ICollection<Nodes> Nodes { get; set; }
        public ICollection<Groups> Groups { get; set;}
        public ICollection<GroupsMember> GroupsMember { get; set; }
        public ICollection<Comment> Comments { get; set; }
        public ICollection<Votes> Votes { get; set; }
        public ICollection<Profiles> Profiles { get; set; }
     }

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Fluent api

protected override void OnModelCreating(System.Data.Entity.DbModelBuilder modelBuilder)
        {  
   modelBuilder.Entity<Votes>()
  .HasRequired(n => n.Nodes)
  .WithMany()
  .HasForeignKey(i => i.NodesId)
  .WillCascadeOnDelete(false);

  modelBuilder.Entity<Votes>()
 .HasRequired(n => n.Comment)
 .WithMany()
 .HasForeignKey(i => i.CommentId)
 .WillCascadeOnDelete(false);
            
  modelBuilder.Entity<Votes>()
 .HasRequired(n => n.Users)
 .WithMany()
 .HasForeignKey(i => i.UsersId)
 .WillCascadeOnDelete(false);

            base.OnModelCreating(modelBuilder);
}

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When i run the application,it shows error :

"ExceptionMessage":"Introducing FOREIGN KEY constraint 'FK_dbo.Votes_dbo.Nodes_NodesId' on table 'Votes' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.\r\nCould not create constraint

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What is the problem that cause the error?How should i make it work as expected?Thanks a lot guys. :)

Here is the codes :

Codes
yonghan79Asked:
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sarabandeConnect With a Mentor Commented:
the error occurred because of class Votes, which has members of Comment, Nodes, and ApplicationUsers. if you delete a  Votes object delete would delete the member objects in the other tables as well what is conflicting with the foreign key definitions of the ID members.

I don't know your design but I think you should store only the ID to the other tables and not member objects. otherwise if you create a Votes object automatically a new comment, node and user object would created, what especially for the user rarely seems to make sense. additionally you have the ID fields which could point to other objects of those 3 tables.

Sara
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sarabandeCommented:
a 'foreign key constraint' would be violated if you add a value to a foreign key column where there is no reference entry in the related table. as the 'Votes' table has 3 foreign keys it would be either 'commentid' that doesn't exist in comments table or 'nodesid' which is missing in nodes table or 'userid' which is not in users table.

from the exception it is the 'nodesid' which is not valid.

note, at insert all these 3 fields must be provided with valid contents cause they were mandatory fields. with the current definition you can't let any of these fields empty (nul value).

Sara
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yonghan79Author Commented:
Hi sara,i'm using ef code first,the error shows when i run the application and register an user.do you have any suggestion for me?thank you.
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sarabandeCommented:
can you post the code executed before the exception was thrown?

Sara
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yonghan79Author Commented:
The application was based on asp.net web api,so i use json to register the user like this :

{"Username":"testing",password":"testing","confirmpassword":"testing","email":yonghan79@gmail.com"}
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yonghan79Author Commented:
Ok,i'll try to recheck the codes.thanks
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