Lithium Filter Example

PostsController.php

<?php

namespace app\controllers;

use \app\models\Post;
use \lithium\util\Inflector;

Post::applyFilter('save', function($self, $params, $chain) {
  // Custom pre-dispatch logic goes here

  //create a slug for new posts.
  if(!($params['entity']->exists())){
    $slug = Inflector::slug($params['data']['title']);
    
    //count of slugs which start with $slug
    $count = Post::find('count', array(
        'fields' => array('id'),
        'conditions' => array('slug' => array('like' => '/^(?:' . $slug . ')(?:-?)(?:\d?)$/i')),
    ));
    $params['data']['slug'] = $slug . ($count ? "-" . (++$count) : ''); //add slug-X only if $count > 0
  }
  
  $response = $chain->next($self, $params, $chain);

  // $response now contains the return value of the dispatched request,
  // and can be modified as appropriate
  // ...
  return $response;
});

Where would this filter be located? In what file? How would it be loaded?

$params['data']['title']; does not return title anymore. you should go with $params['entity']->title;

This was written when I was trying out Lithium, I'm not using Lithium anymore. You can probably fork and update this.