DAO pattern, where to validate?

[[ArcanE]]

I'm thinking of implementing the DAO and VO pattern into my webapplications to serve as my data layer.

That made me think, i need to implement some sort of data validation to prevent the data in my database loosing it's integrity.

Where would i perform this sort of validation? In the DAO or in the VO with setters? Or perhaps completely separate from the DAO and VO in my business layer before i instantiate my DAO and VO objects?

[teampl4y4]

Not sure if this is the best way, but my DAO extend a base class which have a save/update method. The save/method calls my Validation class.. so it kind of looks like this

 //My Controller

 class Controller {
   public method createClient($values) {
     $c = new Client();
     $c->save($values);  
   }
 }

 class Client extends DAO {
public $props = array('ID'=>array('max_length'=>'10','type'=>'int','required'=>'','default'=>'','null'=>'NO'),
'f_name'=>array('max_length'=>'45','type'=>'varchar','required'=>true,'default'=>'','null'=>'NO'),  'l_name'=>array('max_length'=>'45','type'=>'varchar','required'=>'','default'=>'','null'=>'NO'),
'email'=>array('max_length'=>'45','type'=>'varchar','required'=>'','default'=>'','null'=>'NO'),  'userID'=>array('max_length'=>'45','type'=>'varchar','required'=>'','default'=>'','null'=>'NO'),
'propCount'=>5);

    //Extra logic

 }

 class DAO {
   public method save($values) {
      try{
        $this->_validate( $values, $this->props );
      } catch (Exception $e) {
         throw new Exception($e->getMessage());
      }
   }
   protected function _validate($value, $properties) {
      $v = new Validation();
      try {
        $v->validate($values, $properties);
      } catch (Exception $e) {
        throw new Exception($e->getMessage());
      }
   }
 }

 $c = new Controller();
 $c->createClient($clientArray); 

Something like that, I'm sure I forgot something.