In OpenERP first we create user's in user's form. Then the access of user's models res_users and pass the ids of the user's. After passing ids of the user's then user's selection will active and Return a tuple.

Use this function given below

 def select_users(self, cr, uid, context=None):
  
        res = False
        me = self.pool.get('res.users').read(
            cr, uid, uid, ['saved_selection_id'], context=context)
        if me['saved_selection_id']:
            selection_id = me['saved_selection_id'][0]
            selection = self.read(
                cr, uid, selection_id, ['model_id', 'ids'], context)
            model = self.pool.get('ir.model').read(
                cr, uid, selection['model_id'][0], ['model'], context
                )['model']

            domain = [('id', 'in', (
                        selection['ids'] and
                        [int(x) for x in selection['ids'].split(',')] or []))]

            search_context = context and context.copy() or {}
            search_context['active_test'] = False

            ids = self.pool.get(model).search(
                cr, uid, domain, limit=0, context=search_context)

            res = (model, ids)
        return res