By default the Entity Framework does not load references to related entity objects. In this situation, the QueryDetails event exposed by the EntityDetailDescription class can be handled to provide details for a data item. For example, in the code snippet below, a query that will return the appropriate details for a parent item is executed and the Handled property set to true to indicate that the event was handled. In the case where the event is not handled and columns contain references to external Entity objects, the column would have remained empty unless those objects had been cached when loaded by some other means.

Reference

EntityDetailDescription Class
EntityDetailDescription Members