EF code first - Table with 2 or more child relationships of the same type

Question

This has been asked a few times, but solutions I have seen so far have not solved the issue.

I have tables like this.

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

   public int TableBRefAId {get; set;}

   public int TableBRefBId {get; set;}

   [Required]
   public TableB ItemA {get;set;}

   [Required]
   public TableB ItemB {get;set;}
}

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

    public virtual IList<TableA> TableAList { get; set; }
}

and then in the DataContext I have this.

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.Entity<TableA>()
            .HasRequired<TableB>(p => p.ItemA)
            .WithMany(pp => pp.TableAList )
            //.HasForeignKey(x => x.TableBRefAId)
            .WillCascadeOnDelete(false);

        modelBuilder.Entity<TableA>()
            .HasRequired<TableB>(p => p.ItemB)
            .WithMany(pp => pp.TableAList )
            //.HasForeignKey(x => x.TableBRefBId)
            .WillCascadeOnDelete(false);
    }

When I try to run "Add-Migration AddedTableA" I get the following error.

Schema specified is not valid. Errors: The relationship 'TableA_ItemA' was not loaded because the type 'TableB' is not available.

The way I need it to work it that TableA has 2 required properties of TableB.

If TableA is deleted, TableB is not affected.

If TableB is deleted, so is TableA

Answer 1

You should specify two collection for TableB entity to represent two references;

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

    public virtual IList<TableA> TableItemAList { get; set; }

    public virtual IList<TableA> TableItemBList { get; set; }
}

Then;

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<TableA>()
        .HasRequired<TableB>(p => p.ItemA)
        .WithMany(pp => pp.TableItemAList)
        //.HasForeignKey(x => x.TableBRefAId)
        .WillCascadeOnDelete(false);

    modelBuilder.Entity<TableA>()
        .HasRequired<TableB>(p => p.ItemB)
        .WithMany(pp => pp.TableItemBList)
        //.HasForeignKey(x => x.TableBRefBId)
        .WillCascadeOnDelete(false);
}

Answer 2

首先尝试使TableA类中的ItemA和ItemB虚拟，并在TableB类中添加TableA的另一个虚拟列表