/**
*
* @param string $trackingField The field that stores the tracking value
* @param string $trackedField The field whose changing is tracked
* @param string $oldValueField Optional, the field to store a copy of the original value in
*/
public function apply($trackingField, $trackedField, $oldValueField = null)
{
if (null === $oldValueField) {
// Defautl name
$oldValueField = self::OLD_FIELD_PREFIX . $trackedField;
// Check if a fields already existed
if (method_exists($this->_model, 'getKeyCopyName')) {
$copyName = $this->_model->getKeyCopyName($trackedField);
if ($this->_model->has($copyName)) {
$oldValueField = $copyName;
}
}
}
if (!$this->_model->has($oldValueField)) {
$this->_model->set($oldValueField, 'elementClass', 'Hidden', __CLASS__, $trackedField);
$this->_model->setOnLoad($oldValueField, array($this, 'loadOldValue'));
}
if (!$this->_model->has($trackingField)) {
// Only load the original value and ste the original result when it was not already in the model
$this->_model->setAutoSave($trackingField);
// $this->_model->setOnLoad($trackingField, $this->_unchangedValue);
}
$this->_model->set($trackingField, __CLASS__, array($trackedField, $oldValueField));
$this->_model->setOnSave($trackingField, array($this, 'saveValue'));
// Store the extra hidden fields needed
$hiddenFields = $this->_model->getMeta(self::HIDDEN_FIELDS, array());
$hiddenFields[] = $oldValueField;
$this->_model->setMeta(self::HIDDEN_FIELDS, $hiddenFields);
// Make sure the fields are in the result set
$this->_model->get($trackedField);
$this->_model->get($trackingField);
$this->_model->get($oldValueField);
}
