Does PHP Have an Equivalent of Java's RequestDispatcher.forward?

Question

In Java I can write a really basic JSP index.jsp like so:

<% request.getRequestDispatcher("/home.action").forward(request, response); %>

The effect of this is that a user requesting index.jsp (or just the containing directory assuming index.jsp is a default document for the directory) will see home.action without a browser redirect, i.e. the [forward](http://java.sun.com/javaee/5/docs/api/javax/servlet/RequestDispatcher.html#forward(javax.servlet.ServletRequest,%20javax.servlet.ServletResponse)) happens on the server side.

Can I do something similar with PHP? I suspect it's possible to configure Apache to handle this case, but since I might not have access to the relevant Apache configuration I'd be interested in a solution that relies on PHP alone.

Answer 1

If you are concerned about CURL availability then you could use file_get_contents() and streams. Setting up a function like:

function forward($location, $vars = array()) 
{
    $file ='http://'.$_SERVER['HTTP_HOST']
    .substr($_SERVER['REQUEST_URI'],0,strrpos($_SERVER['REQUEST_URI'], '/')+1)
    .$location;

    if(!empty($vars))
    {
         $file .="?".http_build_query($vars);
    }

    $response = file_get_contents($file);

    echo $response;
}

This just sets up a GET, but you can do a post with file_get_contents() as well.

Answer 2

The trick about Request.Forward is that it gives you a clean, new request to the action you want. Therefore you have no residu from the current request, and for example, no problems with scripts that rely on the java eq of $_SERVER['REQUEST_URI'] being something.

You could just drop in a CURL class and write a simple function to do this:

<?php 
/**
 * CURLHandler handles simple HTTP GETs and POSTs via Curl 
 * 
 * @author SchizoDuckie
 * @version 1.0
 * @access public
 */
class CURLHandler
{

    /**
     * CURLHandler::Get()
     * 
     * Executes a standard GET request via Curl.
     * Static function, so that you can use: CurlHandler::Get('http://www.google.com');
     * 
     * @param string $url url to get
     * @return string HTML output
     */
    public static function Get($url)
    {
       return self::doRequest('GET', $url);
    }

    /**
     * CURLHandler::Post()
     * 
     * Executes a standard POST request via Curl.
     * Static function, so you can use CurlHandler::Post('http://www.google.com', array('q'=>'belfabriek'));
     * If you want to send a File via post (to e.g. PHP's $_FILES), prefix the value of an item with an @ ! 
     * @param string $url url to post data to
     * @param Array $vars Array with key=>value pairs to post.
     * @return string HTML output
     */
    public static function Post($url, $vars, $auth = false) 
    {
       return self::doRequest('POST', $url, $vars, $auth);
    }

    /**
     * CURLHandler::doRequest()
     * This is what actually does the request
     * <pre>
     * - Create Curl handle with curl_init
     * - Set options like CURLOPT_URL, CURLOPT_RETURNTRANSFER and CURLOPT_HEADER
     * - Set eventual optional options (like CURLOPT_POST and CURLOPT_POSTFIELDS)
     * - Call curl_exec on the interface
     * - Close the connection
     * - Return the result or throw an exception.
     * </pre>
     * @param mixed $method Request Method (Get/ Post)
     * @param mixed $url URI to get or post to
     * @param mixed $vars Array of variables (only mandatory in POST requests)
     * @return string HTML output
     */
    public static function doRequest($method, $url, $vars=array(), $auth = false)
    {
        $curlInterface = curl_init();

        curl_setopt_array ($curlInterface, array( 
            CURLOPT_URL => $url,
            CURLOPT_CONNECTTIMEOUT => 2,
            CURLOPT_RETURNTRANSFER => 1,
            CURLOPT_FOLLOWLOCATION =>1,
            CURLOPT_HEADER => 0));

        if (strtoupper($method) == 'POST')
        {
            curl_setopt_array($curlInterface, array(
                CURLOPT_POST => 1,
                CURLOPT_POSTFIELDS => http_build_query($vars))
            );  
        }
        if($auth !== false)
        {
              curl_setopt($curlInterface, CURLOPT_USERPWD, $auth['username'] . ":" . $auth['password']);
        }
        $result = curl_exec ($curlInterface);
        curl_close ($curlInterface);

        if($result === NULL)
        {
            throw new Exception('Curl Request Error: '.curl_errno($curlInterface) . " - " . curl_error($curlInterface));
        }
        else
        {
            return($result);
        }
    }

}

Just dump this in class.CURLHandler.php and you can do this:

ofcourse, using $_REQUEST is not really safe (you should check $_SERVER['REQUEST_METHOD']) but you get the point.

<?php
include('class.CURLHandler.php');
die CURLHandler::doRequest($_SERVER['REQUEST_METHOD'], 'http://server/myaction', $_REQUEST);
?>

Ofcourse, CURL's not installed everywhere but we've got native PHP curl emulators for that.

Also, this gives you even more flexibility than Request.Forward as you could also catch and post-process the output.

Answer 3

I believe one of the closest analogous methods would be to use the virtual() function on while running php as an apache module.

virtual() is an Apache-specific function which is similar to in mod_include. It performs an Apache sub-request.

Answer 4

If you use an MVC like the Zend Framework provides you can change the controller action or even jump between controller actions. The method is _forward as described here.

Answer 5

Try this.

function forward($page, $vars = null){
    ob_clean();
    include($page);
    exit;
}

on included page the $vars variable will work as the java request attributes

Answer 6

Concepts Redirect and Forward like in Java, can be achievable in PHP too.

Redirect :: header("Location: redirect.php"); -- (URL in address bar changes)

Forward :: include forward.php ; -- (URL unchanged at address bar)

Its manageable with this & other programming logics

Answer 7

You can use like:

header ("Location: /path/");
exit;

The exit is need just in case some HTML output was sent before, the header() will not work, so you must sent new header before any output to the browser.