JSONPMiddleware.php

<?php
/**
 * JSONP Middleware Class for the Slim Framework
 *
 * @author  Tom van Oorschot <tomvanoorschot@gmail.com>
 * @since  17-12-2012
 *
 * Simple class to wrap the response of the application in a JSONP callback function.
 * The class is triggered when a get parameter of callback is found   
 *
 * Usage
 * ====
 * 
 * $app = new \Slim\Slim();
 * $app->add(new \Slim\Extras\Middleware\JSONPMiddleware());
 * 
 */

namespace Slim\Extras\Middleware;

class JSONPMiddleware extends \Slim\Middleware
{
    public function call()
    {
        $callback = $this->app->request()->get('callback');

        //Fetch the body first
        $this->next->call();

        //If the JSONP callback parameter is set then wrap the response body in the original
        //callback string.
        if(!empty($callback)){
            //The response becomes a javascript response
            $this->app->contentType('application/javascript');

            $jsonp_response = htmlspecialchars($callback) . "(" .$this->app->response()->body() . ")";
            $this->app->response()->body($jsonp_response);
        }
    }
}