Zend_Validate_Between on Another Value - validation

Question

What is the best way to validate a number range based on the value of another form element? If the user selects "percentage" as a discount type, the discount amount should be between 0 and 100, and not 140! The problem seems to be passing in another form element value.
Also, I've viewed other resources, one dealing with a similar topic, but perhaps not all the way relevant.
How to validate a field of Zend_Form based on the value of another field?
Form.php
$isValid = new Application_Model_Validate();
$discount = $this->createElement('text', 'discount')
->setLabel('Discount Amount')
->setDescription("Enter an amount in the format \"200.00\" ")
->setRequired(true)
->setDecorators(array('Description', 'ViewHelper', 'Errors',
array('HTMLTag', array('tag' => 'dd')),
array('Label', array('tag' => 'dt'))));
$discount->addValidators(array(array('Float')), $isValid->isValid(new Zend_Validate_Between(array('min' => '0', 'max' => '100')), $discountType));
$this->addElement($discount);
Application_Model_Validate.php
Require_once 'Zend/Validate/Abstract.php';
class Application_Model_Validate extends Zend_Validate_Abstract
{
/*
* Validation failure message key
*/
const INVALID_PERCENTAGE = 'InvalidPercentage';
/*
* Validation failure message template definitions
*/
protected $_messageTemplates = array(
self::INVALID_PERCENTAGE => 'Please enter a percentage greater than 0 and up to 100.'
);
protected $_percentageOption;
protected $_percentageValue;
/*
* Defined by Zend_Validate_Interface
* Validate the percentage parameters
*/
public function isValid($value, $context = null)
{
$this->_setValue($value);
/*
* If context key is valid, return true
*/
if(is_array($context))
{
if (isset($context['percentage']) && ($value))
{
return true;
}
}
$this->_error(self::INVALID_PERCENTAGE);
return false;
}
If you need anymore information, just say.

Answer 1

I modified your code a bit and added a drop down box:
Form:
$this->addElement('select', 'discounttype');
$this->getElement('discounttype')
->addMultiOptions(
array('percentage' => 'percentage', 'other' => 'other')
);
$discount = $this->createElement('text', 'discount')
->setLabel('Discount Amount')
->setRequired(true);
$discount->addValidators(
array('Float', new Application_Model_Validate(0, 140))
);
$this->addElement($discount);
Validator:
<?php
class Application_Model_Validate extends Zend_Validate_Between
{
public function isValid($value, $context = null)
{
$this->_setValue($value);
if ($context['discounttype'] == 'percentage') {
$this->setMax(100);
}
return parent::isValid($value, $context);
}
}
Now, if you validate the form in your controller using $form->isValid($this->getRequest()->getParams()), it will take an input between 0 and 100 if in the drop down box 'percentage' is selected and an input between 0 and 140 otherwise.

Answer 2

An alternative solution:
//controller validation
$discountValidate = new Application_Model_Validate();
$discountValidate->_checkDiscount($data['discountType'], $data['discount']);
if ($discountValidate->isValid())
{
//do
}
else
{
$element = $form->getElement('discount');
$element->addError($discountValidate->getError());
}