In Kohana, you are able to add validation rules to a model. This is truly awesome, BUT displaying the validation error is not so automatic out of the box.

In your model you can set up rules like:

public function rules()
{
	return array(
		'username' => array(
			array('not_empty')
			
				
		),			
	);
}

If this is all you have and username is submitted as empty, kohana will throw an ugly exception “Failed to validate array”. What we need to do is set up a message to show if this situation ever happens. If your model is “user” create the file “user.php” in /application/messages. In that file set the messages:

return array
  (
     'username' => 'You submitted an empty username. Please fill it in.'
  );

Then, before you are about to save username to a user model:

$user->username = $username_submitted;
if(!$user->validation->check())
{
   //DISPLAY ERROR HERE
   foreach($user->validation()->errors('user') as $error)
   {
	echo $error;
	
   }
}
else
{
   $user->save();
}

Hopefully Kohana will include better, prettier, and automatic validation layers in future releases but in the current, it’s not too bad.