How to use the composite key of one table as a foreign key to the composite key of another?

Question

Entity Framework

Used by Entity Framework 6, CodeFirst, MS SQL, Asp.Net MVC
There is a simple table, prices (for services) in orders

public class PriceInOrder
{
    public int Order_Id { get; set; }
    public int Price_Id { get; set; }
    public decimal Count { get; set; }
}

The first two fields are a composite key, as described in OnModelCreating

protected override void OnModelCreating(DbModelBuilder _)
{
    ...
    _.Entity<PriceInOrder>().HasKey(e => new {e.Order_Id, e.Price_Id});
    ...
}

Now it was required to add workers who are for each service in the order.

public class UsersInPriceOrders
{
    public string User_Id { get; set; }
    public int Order_Id { get; set; }
    public int Price_Id { get; set; }
}

and added a contact code

protected override void OnModelCreating(DbModelBuilder _)
{
...
_.Entity<UsersInPriceOrders>().HasKey(u => new {u.User_Id, u.Order_Id, u.Price_Id});
_.Entity<UsersInPriceOrders>()
    .HasRequired(u => u.User)
    .WithMany()
    .HasForeignKey(e => e.User_Id).WillCascadeOnDelete(false);

_.Entity<UsersInPriceOrders>()
   .HasRequired(u => u.PriceInOrder)
   .WithMany()
   .HasForeignKey(u => new {u.Order_Id, u.Price_Id}).WillCascadeOnDelete(false);
...
}

This migration came out of this

public override void Up()
{
    CreateTable(
        "dbo.UsersInPriceOrders",
         c => new
            {
                User_Id = c.String(nullable: false, maxLength: 128),
                Order_Id = c.Int(nullable: false),
                Price_Id = c.Int(nullable: false),
            })
        .PrimaryKey(t => new { t.User_Id, t.Order_Id, t.Price_Id })
        .ForeignKey("dbo.PriceOrders", t => new { t.Price_Id, t.Order_Id })
        .ForeignKey("dbo.AspNetUsers", t => t.User_Id)
        .Index(t => t.User_Id)
        .Index(t => new { t.Order_Id, t.Price_Id });         
}

The problem is that when rolling this migration, an error occurs

Referenced table 'dbo.PriceOrders' is missing primary or candidate keys that match the list of referenced columns in the foreign key

At the same time, the composite primary key in this table is
What am I doing wrong?

Answer 1

There is a composite primary key in this table. What am I doing wrong?

Don't use a composite key. [ID] [int] IDENTITY(1,1) NOT NULL is fine.

MICROSOFT SQL SERVER ENTITY FRAMEWORK

Use MS SSMS.