How do insert more than one row into a table using Entity Framework when one column is a foreign key?

Question

Please help me. I can't find this anywhere. I want to do this with Entity framework when inserting:

• Add 1 row to table tParent
• Add 4 rows to table tChildren.

tChildren has a column that is a FK of tParent called ParentID.

I'm on 4.0 framework.

Answer 1

You will have to add the children to the parent using a loop but need to call save changes once, something like as follows, say the parent is Order and child is called OrderItem

    public void AddOrder(OrderDto orderToAdd)
    {
        var newOrder = Order.CreateOrder(orderToAdd.OrderID, .....);  //set all other non nullable attributes
        neworder.OrderDate = orderToAdd.OrderDate;
        //set other properties
        '
        '  
        //then add the order items to the newOrder 
        //note orderToAdd.OrderItemsDto is the ChildList
        foreach (OrderItemDto o in orderToAdd.OrderItemsDto)
        {  
            var orderItem = OrderItem.CreateOrderItem(orderToAdd.OrderID, o.OrderItemID); //set all other non nullable attributes
            orderItem.OrderQuantity = o.OrderQuantity;
            //set other properties
            '  
            '    
            newOrder.OrderItems.Add(orderItem); 
        }
        context.AddToOrders(newOrder);
        context.SaveChanges();
    }

Answer 2

The key is that you have navigational properties setup on the entities.

tParent should have a navigational property called tChildrens, and (optionally), tChildren should have a navigational property called tParent.

The multiplicity should be tParent 1..* tChildren.

With that in mind, this should do the trick:

var parent = new tParent();
var child1 = new tChild();
var child2 = new tChild();
// set properties you need, etc etc
parent.tChildrens.Add(child1);
parent.tChildrens.Add(child2);
context.SaveChanges();

EF is smart enough to add the parent, grab the identity, then insert the children with the FK set to the identity just created.