I have a little complex model, about EF cascade delete - entity-framework

Question

Code first,and model look like this Figure:
public class Post
{
public int Id { get; set; }
public string title { get; set; }
public int fid { get; set; }
public int uid { get; set; }
public virtual lnk lnk { get; set; }
public virtual user user { get; set; }
public virtual ICollection<img> imgs { get; set; }
}
public class lnk
{
public int Id { get; set; }
public string lnkman { get; set; }
}
public class model1:Post
{
public string content { get; set; }
}
public class user
{
public int uid { get;set; }
public string Name {get;set;}
public virtual ICollection<Post> posts { get; set; }
}
public class img
{
public int id { get; set; }
public string imgUrl { get; set; }
public int pid { get; set; }
public virtual Post post { get; set; }
}
public class PostContext : DbContext
{
public DbSet<Post> posts { get; set; }
public DbSet<user> users { get; set; }
public DbSet<img> imgs { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Post>().HasKey(i=>i.Id);
modelBuilder.Entity<lnk>().HasKey(i => i.Id);
modelBuilder.Entity<Post>().HasRequired(i => i.lnk).WithRequiredPrincipal();
modelBuilder.Entity<Post>().ToTable("Post");
modelBuilder.Entity<lnk>().ToTable("Post");
modelBuilder.Entity<model1>().ToTable("model1");
modelBuilder.Entity<user>().HasKey(i => i.uid).ToTable("user");
modelBuilder.Entity<user>().HasMany(i => i.posts)
.WithRequired(i => i.user)
.HasForeignKey(i =>i.uid).WillCascadeOnDelete(false);
modelBuilder.Entity<img>().HasKey(i => i.id).ToTable("img");
modelBuilder.Entity<Post>().HasMany(i => i.imgs)
.WithRequired(i => i.post)
.HasForeignKey(i => i.pid)
.WillCascadeOnDelete(false);
}
}
the add and list method work well. but delele like this :
using (var db = new PostContext())
{
//model1 ToDel = new model1{ Id=id };
//b.Entry(ToDel).State = System.Data.EntityState.Deleted;
var ToDel = db.users.Single(i => i.uid == id);
db.users.Remove(ToDel);
db.SaveChanges();
return id + "DE: well done!" ;
}
System.Data.SqlClient.SqlException: DELETE statement with REFERENCE constraint "FK_dbo.Post_dbo.user_uid" conflict。The conflict occurred in database "jefunfl"，table "dbo.Post", column 'uid'
I want delete users with user's posts, and posts with post's imgs.
How can I do this? Can some one give any tips?
btw,my Chinese English may be funny. forgive me.
this is my first post,but I am not new guy. thanks

Answer 1

bypass all one day, i found it. and thank you for answer to me.
1:
i delete WillCascadeOnDelete() method,so let ef do it by Conventions.
2:
i found that ,when i delete the posts,i can't directly delete with this statement like ToDel = db.posts.Single(i => i.Id == id)
but this:
ToDel = db.posts.Include(i=>i.lnk).Single(i => i.Id == id)
post and lnk has a relatialship that is called table splitting. both mapping to the same post table. when delete posts, EF can auto delete post.imgs by conventions. what will happen when delete user ? and so i got it. my code blow:
var ToDel = db.users.Include(i => i.posts)
.Single(i => i.uid == id);
var PostToDel = db.posts.Include(i => i.lnk)
.Single(i => i.Id == ToDel.uid);
db.posts.Remove(PostToDel);
db.users.Remove(ToDel);
db.SaveChanges();
this will work well. even not perfectly. but it can do what i want without a exception.
at last,the biggest problem is post class and lnk class has a "table splitting".
when delete post we should explicitly include.
i dont know if you can understand me, my english is very ugly. i am foolish with courage.
thank u. i am happy