Question

I have a database similar to below:

Order
===============
OrderID
Description
EmployeeID
...other fields


Product
===============
ProductID
...other fields


OrderProducts
===============
OrderID
ProductID


Employee
===============
EmployeeID
...other fields

I’m using Linq to Entities and the edmx file has been created without the OrderProducts table, as it is just a joining table. The Products table is a list of static products – I dont need to insert any rows at the moment. The Order table I can insert rows successfully using the following code:

[Serializable]
public class MyOrderObject
{
   public int OrderID { get; set; }
   public string OrderDescription { get; set; }
   public int? EmployeeID { get; set; }
   public IEnumerable<MyProductObject> ProductsList { get; set; }
   ...other fields
}

[Serializable]
public class MyProductObject
{
   public int ProductID { get; set; }
   ...other fields
}


private static void AddNewOrder(MyOrderObject order)
{
   using (var context = DatabaseHelper.CreateContext())
   {
      var dbOrder = new Order
      {
         OrderID = order.OrderID,
         Description = order.OrderDescription,
         Employee = context.Employees.SingleOrDefault(x => x.EmployeeID == order.EmployeeID),
      }
      context.AddToOrders(dbOrder);
      context.SaveChanges();
   }
}

How do I insert into the database my list of child relationship records??
I’ve tried:

List<int> ProductIDs = order.ProductsList.Select(x => x.ProductID).ToList();
//dbOrder.Products.Attach(context.Products.Where(x => ProductIDs.Contains(x.ProductID)));
//or dbOrder.Products = context.Products.Where(x => ProductIDs.Contains(x.ProductID));
//or dbOrder.Products = context.Products.Contains(ProductIDs);
//or foreach(var p in order.ProductsList)
//   {
//      context.AttachTo("Products", new Product { ProductID = p.ProductID });
//   }

Answer 1

No need to change the object type:

var dbOrder = new Order
{
   OrderID = order.OrderID,
   Description = order.OrderDescription,
   Employee = context.Employees.SingleOrDefault(x => x.EmployeeID == order.EmployeeID),
}

//this adds the relationship to the child without adding a new child record - perfect!
foreach(var p in order.ProductsList)
{
   dbOrder.Products.Add(p);
}

context.AddToOrders(dbOrder);
context.SaveChanges();