Question

I am using EF 4.1 code first and have problem updating Order entity, when the existing entity contains a not null collection of OrderList and user has removed a few of the existing and added a new order list.

I have the domain model as shown below

public class Order
{
    public int Id { get; set;
    public string Name { get; set;}

    public ICollection<OrderList> OrderLists { get; set;}
}

public class OrderList
{
    public int Id { get; set;}
    public int OrderId { get; set;}
    public string ItemDescription { get; set;}
    public decimal Price { get; set;}

    public virtual Order Order { get; set;}
}

This is the code i am using for updating the Order entity.

using (var context = new MyDbContext())
{
    var order = context.Orders
                        .Include("OrderLists")
                        .FirstOrDefault(o => o.Id == orderId);

    order.Name = "New name"; // this gets saved
    order.OrderLists.Clear(); // Does not delete the existing order list items
    order.OrderLists = new List<OrderList> { new OrderList { OrderId = order.Id, ItemDescription = "New Item" } };  // Does not create new list

    context.Orders.Attach(order);
    context.Entry<Order>(order).State = System.Data.EntityState.Modified;
    context.ChangeTracker.DetectChanges();
    context.SaveChanges();
}

Please some guide me on how I can acheive this using EF 4.1 code first?

Thanks
Guru

Answer 1

This should do the trick:

var order = context.Orders
                    .Include("OrderLists")
                    .FirstOrDefault(o => o.Id == orderId);
order.Name = "New name"; // this gets saved

foreach (var orderlist in order.OrderLists.ToList())
{
    context.OrderLists.Remove(orderlist);
}

order.OrderLists.Clear();                 

order.OrderLists.Add(new OrderList { Id = order.Id, ItemDescription = "New Item" });

context.SaveChanges();

You need to delete the orderlist items individually and then clear the collection.