So I have a client that needs to interchange some XML data with a customer.  The XML document exchanged is fairly hierarchical except for one field.

This fragment of XML represents the flat structure:

 <ShipFrom>
  <Name />
  </ShipFrom>
 <LineItem>
  <Qty>0</Qty>
  <ItemId>Item A</ItemId>
  <Serial>1234</Serial>
  <ReceivedQty>1</ReceivedQty>
  </LineItem>
 <LineItem>
  <Qty>0</Qty>
  <ItemId>Item B</ItemId>
  <Serial>3211</Serial>
  <ReceivedQty>1</ReceivedQty>
  </LineItem>
 <OrderTrailer>
  <TotalQty>1</TotalQty>
  </OrderTrailer>

I have a nice object hierachy that deserializes this XML to a set of properties (sub objects).  However the LineItem nodes really should be surrounded by a parent node to better represent an array or list of these items.  The customer can not change their end so I must work around the problem.  I want this list of <LineItem> nodes to deserialize into a List<LineItem> property and serialize flat like in the XML above.

As it turns out, the solution is remarkably simple.  In the class definition simply decorate the List<LineItem> property with the [XmlElementAttribute] attribute and the XmlSerializer will handle flattenting out and inflating for you.

private List<LineItem> _LineItem;

[XmlElementAttribute]
public List<LineItem> LineItem
{
      get { return _LineItem; }
      set { _LineItem = value; }
}

So the code above is the only change to my class and it now serializes the generic list flat to XML and handles deserializing the list perfectly.

http://msdn.microsoft.com/en-us/library/2baksw0z(VS.80).aspx