public function buildChain()
 {
     $chain = new ValidatorChain();
     $dateTimeValidator = new DateTimeValidator();
     $notEmptyValidator = new NonEmptyValidator();
     $integerValidator = new IntegerValidator();
     $chain->addValidators('checkinDate', array($dateTimeValidator, $notEmptyValidator, new ActualDateTieValidator()));
     $chain->addValidators('checkoutDate', array($dateTimeValidator, $notEmptyValidator, new DateIntervalValidator('checkinDate', 'checkoutDate')));
     $chain->addValidator('guestsCount', $integerValidator);
     $chain->addValidators('priceString', array($notEmptyValidator, new PriceValidator()));
     $chain->addRequiredFields(array('checkinDate', 'guestsCount', 'checkoutDate', 'priceString', 'pageId'));
     return $chain;
 }