Entity Framework Itself referention -> parent/child [duplicate]

Question

Is it possible to set parent/child relations using EF Core and fluent api?

I have following class

public class Category 
{
   public int Id { get; set; }
   public int ParentId { get; set; }
   public string Name { get; set; }
   public ICollection<Category> SubCategories { get; set; }
}

So if I create list of objects with have structure as below, it is possible that, EF set entitie's id, and parentId with appropriate numbers?

• Cat 1
  • Cat 2
    • Cat 3
  • Cat4
  • Cat5

Answer 1

You can just reference your own class:

public class Category 
{
   public int Id { get; set; }
   public int? ParentId { get; set; }
   public Category Parent { get; set; }
   public string Name { get; set; }
   public ICollection<Category> SubCategories { get; set; }
}

You can also set it up further with fluent api:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
  modelBuilder.Entity<Category>()
            .HasMany(j => j.SubCategories)
            .WithOne(j => j.Parent)
            .HasForeignKey(j => j.ParentId)
}