title: Should the properties in Data Transfer Object expand the foreign keys or simply expose their primary keys
body: <p>I have an EmployeeDTO that respresents an Employee record in the database.   The Employee table has a relationship to a Department and a 1-to-many relationship to Permission.</p>
  
  <p>In my entities, these are represented as a fully expanded Department property and a List of fully expanded permission objects.</p>
  
  <p>The question is should the DTO have a fully expanded DepartmentDTO property of a DepartmentId?   Should the DTO have a list of fully expanded PermissionDTO properties of List of PermissionId?</p>