public function rules()
{
// NOTE: you should only define rules for those attributes that
// will receive user inputs.
return array(array('event_id, eye_id', 'safe'), array('id, event_id, eye_id', 'safe', 'on' => 'search'), array('left_readings', 'requiredIfSide', 'side' => 'left'), array('right_readings', 'requiredIfSide', 'side' => 'right'));
}