see here: https://www.odoo.com/forum/help-1/question/how-to-display-group-column-with-no-data-in-openerp-7s-kanban-view-30469
By the way solution is
def _read_group_drivers(self, cr, uid, ids, domain, read_group_order=None, access_rights_uid=None, context=None):
#search and pass one2many fieldsid and name in list for ex = [(id1,'name'),(id2, 'name2')] and fold
all_drivers = self.pool.get('soohoo.driver').search(cr, uid, [])
#for driver in all_drivers:
_logger.warning('drivers--------- %s ' %all_drivers)
result = [(driver.id, driver.name) for driver in self.pool.get('soohoo.driver').browse(cr, uid, all_drivers)]
fold = dict.fromkeys(range(1,len(result)+1), False)
_logger.warning('here---- %s ----and---- %s' %(result, fold))
return result, fold
_group_by_full = {
'driver': _read_group_drivers
}