Form validation messages

SomeForm.php

<?php
class SomeForm extends Form {

  function validate(){
		if($this->validator){
			$errors = $this->validator->validate();

			if($errors){
				if(Director::is_ajax() && $this->validator->getJavascriptValidationHandler() == 'prototype') {
					FormResponse::status_message(_t('Form.VALIDATIONFAILED', 'Validation failed'), 'bad');
					foreach($errors as $error) {
						FormResponse::add(sprintf(
							"validationError('%s', '%s', '%s');\n",
							Convert::raw2js($error['fieldName']),
							Convert::raw2js($error['message']),
							Convert::raw2js($error['messageType'])
						));
					}
				} else {
					$data = $this->getData();

					$formError = array();
					if ($formMessageType = $this->MessageType()) {
					  $formError['message'] = $this->Message();
					  $formError['messageType'] = $formMessageType;
					}

					// Load errors into session and post back
					Session::set("FormInfo.{$this->FormName()}", array(
					  'errors' => $errors,
					  'data' => $data,
					  'formError' => $formError
					));

				}
				return false;
			}
		}
		return true;
	}

}

SomeValidator.php

<?php
class SomeValidator extends RequiredFields {

	function php($data) {

	    $valid = parent::php($data);
	    $fields = $this->form->Fields();
		
	    $this->form->sessionMessage(
  		  'This message should be displayed as an error for the form.',
  		  'bad'
            );
  		
            //Have to set errors for validate()
  	    $this->errors[] = true;
  	    $valid = false;

	    return $valid;
	}
}