How to relate model property to same model in ASP.NET MVC? - asp.net-mvc

Question

Sometimes, you want to store who registered or created a user account. It's either the user registered himself/herself or some other user account registered him, such as Admin accounts. So, the User table would something like:
public class User : Identity
{
public int Id { get; set; }
public string UserName { get; set; }
public string Email { get; set; }
public string Name { get; set; }
// this is the part that I'd to relate to the same model
[ForeignKey("Id")]
public virtual User RegisteredBy { get; set; }
}
Using data annotations or Fluent API, how would you relate the User.RegisteredBy to User.Id?
Thanks in advance!

Answer 1

Something like in your class
public class User : Identity
{
public int Id { get; set; }
public string UserName { get; set; }
public string Email { get; set; }
public string Name { get; set; }
// this is the self referential part
public int? RegisteredById { get; set; }
public virtual User RegisteredBy { get; set; }
public virtual ICollection<User> RegisteredUsers { get; set; }
}
and then in your DbContext
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<User>()
.HasOptional(x => x.RegisteredBy)
.WithMany(x => x.RegisteredUsers)
.HasForeignKey(x => x.RegisteredById);
}
This is untested, but I did something similar in a project a little while ago and it worked fine.

Answer 2

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<User>()
.HasOptional(c => c.RegisteredBy)
.WithMany()
.HasForeignKey(c => c.RegisteredById);
}
You can use the above Fluent Api code and your class should look like this
public class User : Identity
{
public int Id { get; set; }
public string UserName { get; set; }
public string Email { get; set; }
public string Name { get; set; }
public int? RegisteredById { get; set; }
public User RegisteredBy { get; set; }
}