Question

Supposing I have two classes, Customer and Order, where one Customer can have one-or-many Orders associated to it.

class Customer
{
  Order[] Orders;
}

class Order
{
  int OrderId;
}

If for any given Customer, I want to find all the associated OrderId’s, is there an easy way to do that using linq ? Something that gives the same result as the following foreach solution:

List<int> allOrderIds = new List<int>();
foreach (Order thisOrder in thisCustomer)
{
   allOrderIds.Add(thisOrder.OrderId);
}

TIA.

Answer 1

var allOrderIds = thisCustomer.Orders.Select(o => o.OrderId).ToList();