'Lazy load services attribute.'

def obj_load_attr(self, attrname):

    if (attrname != 'services'):
        raise exception.ObjectActionError(action='obj_load_attr', reason=(_('attribute    %s    not    lazy-loadable') % attrname))
    if (not self._context):
        raise exception.OrphanedObjectError(method='obj_load_attr', objtype=self.obj_name())
    self.services = objects.ServiceList.get_all(self._context, {'cluster_name': self.name})
    self.obj_reset_changes(fields=('services',))
