def set_has_many_attr(col, *instances)
      _col = column(col)
      unload_relation(_col)
      push_has_many_attr(_col, *instances)
      instances
    end
def set_has_many_attr(col, *instances)
      _col = column(col)
      unload_relation(_col)
      push_has_many_attr(_col, *instances)
      instances
    end
TODO clean up existing reference, check rails