CakePHP 1.2 custom validation. Unique behavior.

As you know cakephp 1.2 allow to call custom functions during validation.

var $validate = array( 	'alias' => array(
		'rule' => array('unique', 'alias'),
		'required' => true, 'allowEmpty' => false,
		'message' => 'Such alias already exists' 	),
);

This is sample when you need to have unique field in whole table.

 function unique($data, $name){
  $this->recursive = -1;
  $found = $this->find(array(“{$this->name}.$name” => $data));
  $same = isset($this->id) && $found[$this->name][$this->primaryKey] == $this->id;
  return !$found || $found && $same;
 }

This example from cakebaker blog.