private GroceryList getGroceryList(final EntityManager em, final User user) {
final TypedQuery<GroceryList> q = em.createNamedQuery("groceryListsForUser", GroceryList.class);
q.setParameter("user", user);
final List<GroceryList> groceryLists = q.getResultList();
final GroceryList gl;
if (groceryLists.isEmpty()) {
gl = new GroceryList();
gl.setOwner(user);
em.persist(gl);
em.flush();
}
else {
gl = groceryLists.get(0);