<?php
class AppModel extends Model
{

	// First, we override save(). On a successful save(), 
	// afterSave() is called. But we want something to be 
	// called on a NOT-successful save().
	function save($data = null, $validate = true, $fieldList = array()) {
		$returnval = parent::save($data, $validate, $fieldList);
		if(false === $returnval) {
			$this->afterSaveFailed();
		}
		return $returnval;
	}

	// This is a stub which is called after a save has failed. 
	// You will override this in the model.
	function afterSaveFailed() {
	}

	// This is a (MySQL specific) check to see if a 
	// constraint was violated as the last error. If it was,
	// the VALUE of the field which failed is returned.
	// this is not ideal, but will do for most situations.
	// The logic to work out the specific field which failed
	// requires more MySQL specific SQL (such as 'show keys from...'
	// so I shall leave it out. Most tables only have one 
	// unique constraint anyway, although our example above
	// has 2.
	function checkFailedConstraint() {
		$db =& ConnectionManager::getDataSource($this->useDbConfig); 
		$lastError = $db->lastError();

		// this is MYSQL SPECIFIC
		if(preg_match('/^\d+: Duplicate entry \'(.*)\' for key \d+$/i', $lastError, $matches)) {
			return $matches[1];
		}

		return false;
	}

}
?>