Having a List<T>, How to get Other Fields from DB?

Question

Hi I have a method named "GetOrders". This method reads an XML file and gathers OrderNumber of all orders related to a specific user. The method returns a list.

Now I wanna to know, having my list, How can I get other fields of these OrderNumbers from DB?

Answer 1

If you use LINQ to SQL, it is trivial. I'll assume that you already have the designer-generated tables and your list (though why you're keeping it in XML is a curiosity, it seems more reasonable to keep it in the database as well).

 var orderNumbers = ... your list ...

 using (var dataContext = new OrdersDataContext()) // designer-generated context
 {
     var orderTitles = dataContext.Orders
                                  .Where( o => orderNumbers.Contains( o.OrderNumber ) )
                                  .Select( o => o.OrderTitle );

     ... now do something with the collection...
 }

Answer 2

GetOrders needs to de-serialize the Orders into Order Objects and return these (not just the Order Numbers) So the List (Return Type) you want returned by GetOrders() is List.

eg; List orders = GetOrders();

Then you can iterate through the Orders and get the other fields eg:

foreach(Order order in orders) { string orderNumber = order.OrderNumber; Guid id = order.ID; }