@Test
  public void testExistsQuery() {
    ExistsQueryTestModel m = ExistsQueryTestModel.q().filter("bags.z exists", true).get();
    assertNull(m);

    m = ExistsQueryTestModel.q().filter("bags.a exists", true).get();
    assertNotNull(m);
  }
 @Before
 public void setup() {
   ExistsQueryTestModel.deleteAll();
   model = new ExistsQueryTestModel();
   String[] keys = {"a", "b", "c"};
   for (String s : keys) {
     model.addStuff(s);
   }
   model.save();
 }