Asp.Net MVC Codefirst Model Relation to the Same Model - asp.net-mvc

Question

I have a model and i want to put an extra field which can be populated form the same model. IE: Categories and and sub-categories.
In my example, visitor can add an filetype but if file type is under an another file type, he can choose,
But i cant work it out. Below you can see my model.
public class HrFileType
{
[Key]
public int Id { get; set; }
[Display(Name = "Dosya Adı")]
public int Name { get; set; }
public int? HrFileTypeId { get; set; }
public virtual HrFileType HrFileType2 { get; set; }
}

Answer 1

You just need to add a ForeignKeyAttribute like below:
public class HrFileType
{
[Key]
public int Id { get; set; }
[Display(Name = "Dosya Adı")]
public int Name { get; set; }
public int? HrFileTypeId { get; set; }
[ForeignKey("HrFileTypeId")]
public virtual HrFileType HrFileType2 { get; set; }
}
You can also use fluent API to achieve this:
public class HrFileType
{
[Key]
public int Id { get; set; }
[Display(Name = "Dosya Adı")]
public int Name { get; set; }
public int? HrFileTypeId { get; set; }
public virtual HrFileType HrFileType2 { get; set; }
}
public class YourDbContext : DbContext
{
public DbSet<HrFileType> HrFileTypes { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
//
modelBuilder.Entity<HrFileType>()
.HasOptional(c => c.HrFileType2)
.WithMany()
.HasForeignKey(c => c.HrFileTypeId);
}
}

Answer 2

Have you tried listing the other file types?
public class HrFileType
{
[Key]
public int Id { get; set; }
[Display(Name = "Dosya Adı")]
public int Name { get; set; }
public List<HrFileType> RelatedTypes { get; set; }
}
then using Entity Frameworks fluent API in the DbContext, try explicitly declaring a many to many map.
modelbuilder.Entity<HrFileType>().HasMany(x => x.RelatedTypes).WithMany();
I'd be very interested to see if this works. It's the only logical solution I can think of without having some kind of parent class.