<?php 
class App_Form_Validators_MongoBooleanRequired extends Zend_Validate_Abstract
    {
        const REQUIRED_VALUE = 'required_mongo_boolean_value';

	    protected $_messageTemplates = array(
	        self::REQUIRED_VALUE=> "Il campo deve essere di true o false"
	    );
     
        public function isValid($value)
        {
            $this->_setValue($value);
     
            $isValid = true;

            if($value !== true && $value !== false){
                $this->_error(self::REQUIRED_VALUE);
                $isValid = false;
            }

            return $isValid;
        }
    }