In OpenERP, first we create registration in event form and then pass the param ids like as list of event registration's IDs and also mapp to the standard dictionary for contextual values than we create email for users and validate to the event form.

Use this function show below:

def check_confirm(self, cr, uid, ids, context=None):
       
        if type(ids) in (int, long,):
            ids = [ids]
        data_pool = self.pool.get('ir.model.data')
        unconfirmed_ids = []
        if context is None:
            context = {}
        for registration in self.browse(cr, uid, ids, context=context):
            total_confirmed = registration.event_id.register_current + registration.nb_register
            if total_confirmed <= registration.event_id.register_max or registration.event_id.register_max == 0:
                self.do_open(cr, uid, [registration.id], context=context)
            else:
                unconfirmed_ids.append(registration.id)
        if unconfirmed_ids:
            view_id = data_pool.get_object_reference(cr, uid, 'event', 'view_event_confirm_registration')
            view_id = view_id and view_id[1] or False
            context['registration_ids'] = unconfirmed_ids
            return {
                'name': _('Confirm Registration'),
                'context': context,
                'view_type': 'form',
                'view_mode': 'tree,form',
                'res_model': 'event.confirm.registration',
                'views': [(view_id, 'form')],
                'type': 'ir.actions.act_window',
                'target': 'new',
                'context': context,
                'nodestroy': True
            }
        return True