Entity Framework - Multiple Many-To-Many Relationships

Question

I am trying to describe the mapping to EF to create multiple many-to-many relationships between the following two entities (simplified):

Product:

public class Product
    {
        [Key]
        public int ProductID { get; set; }

        public string ProductName { get; set; }
        public decimal Price { get; set; }

        public virtual ICollection<Transaction> Transactions { get; set; }
        public virtual ICollection<Transaction> RefundTransactions { get; set; }
        public virtual ICollection<Transaction> VoidTransactions { get; set; }
    }

Transaction:

public class Transaction
{
    [Key]
    public int TransactionID { get; set; }

    public virtual ICollection<Product> Products { get; set; }
    public virtual ICollection<Product> RefundProducts { get; set; }
    public virtual ICollection<Product> VoidProducts { get; set; }
}

OnModelCreating:

        modelBuilder.Entity<Transaction>()
            .HasMany(m => m.Products)
            .WithMany(t => t.Transactions)
            .Map(m =>
            {
                m.ToTable("Transaction_Product_Mapping");
                m.MapLeftKey("TransactionID");
                m.MapRightKey("ProductID");
            }
        );

        modelBuilder.Entity<Transaction>()
            .HasMany(transaction => transaction.VoidProducts)
            .WithMany(t => t.VoidTransactions)
            .Map(m =>
            {
                m.ToTable("Transaction_Void_Product_Mapping");
                m.MapLeftKey("TransactionID");
                m.MapRightKey("VoidProductID");
            }
        );

        modelBuilder.Entity<Transaction>()
            .HasMany(m => m.RefundProducts)
            .WithMany(t => t.Transactions)
            .Map(m =>
            {
                m.ToTable("Transaction_Refund_Product_Mapping");
                m.MapLeftKey("TransactionID");
                m.MapRightKey("RefundProductID");
            }
        );

Exception:

 Type Transaction_Products is not defined in namespace Nautix_EPOS.Models

Now, I think this may be because I am defining the mapping 3 times separately. And possibly overwriting the first with the second, and the second with the last.

Question:

How can I tell EF about the multiple many-to-many mappings between the same two tables?

Answer 1

I figured it out, it's because I used the same t.Transactions in the first and third declaration. I should have use t.RefundTransactions :

    modelBuilder.Entity<Transaction>()
        .HasMany(m => m.Products)
        .WithMany(t => t.Transactions)
        .Map(m =>
        {
            m.ToTable("Transaction_Product_Mapping");
            m.MapLeftKey("TransactionID");
            m.MapRightKey("ProductID");
        }
    );

    modelBuilder.Entity<Transaction>()
        .HasMany(transaction => transaction.VoidProducts)
        .WithMany(t => t.VoidTransactions)
        .Map(m =>
        {
            m.ToTable("Transaction_Void_Product_Mapping");
            m.MapLeftKey("TransactionID");
            m.MapRightKey("VoidProductID");
        }
    );

    modelBuilder.Entity<Transaction>()
        .HasMany(m => m.RefundProducts)
        .WithMany(t => t.RefundTransactions)
        .Map(m =>
        {
            m.ToTable("Transaction_Refund_Product_Mapping");
            m.MapLeftKey("TransactionID");
            m.MapRightKey("RefundProductID");
        }
    );