Question

public class User
{
   public int Id {get;set;}

   public string Name {get;set}

   public ICollection<User> Followers {get;set;}
   public ICollection<User> Following {get;set;}
}

My Model looks like above, Entity framework automatically creates A table and UserUser with rows User_ID and User_ID1 in DB to map this model. I want to map that table and rows myself.

How can i do that, Thanx!!

Answer 1

From Scott Gu’s blog about Many-valued Associations:

Many-to-Many Associations
The association between Category and Item is a many-to-many
association, as can be seen in the above class diagram. a many-to-many
association mapping hides the intermediate association table from the
application, so you don’t end up with an unwanted entity in your
domain model. That said, In a real system, you may not have a
many-to-many association since my experience is that there is almost
always other information that must be attached to each link between
associated instances (such as the date and time when an item was added
to a category) and that the best way to represent this information is
via an intermediate association class (In EF, you can map the
association class as an entity and map two one-to-many associations
for either side.).

In a many-to-many relationship, the join table (or link table, as some
developers call it) has two columns: the foreign keys of the Category
and Item tables. The primary key is a composite of both columns. In EF
Code First, many-to-many associations mappings can be customized with
a fluent API code like this:

    class ItemConfiguration : EntityTypeConfiguration<Item> {
    internal ItemConfiguration()
    {
        this.HasMany(i => i.Categories)
            .WithMany(c => c.Items)
            .Map(mc =>
            {
                mc.MapLeftKey("ItemId");
                mc.MapRightKey("CategoryId");
                mc.ToTable("ItemCategory");
            });
    } }

Register this configuration in your DbContext’s (you using the DbContext api right?) like this:

  protected override void OnModelCreating(ModelBuilder modelBuilder)
  {
    base.OnModelCreating(modelBuilder);

    modelBuilder.Configurations.Add(new ItemConfiguration());
  }

Good luck, hope this help!