Solve the issue that output_add_rewrite_var cannot rewrite the URL correctly

gitbox 2025-05-29

1. Introduction to the working principle of output_add_rewrite_var

output_add_rewrite_var is a built-in function in PHP that is used to automatically append a specified query variable and its value to all output URLs. Common usage is as follows:

 <?php
session_start();
output_add_rewrite_var('PHPSESSID', session_id());
?>

This function will scan all URLs in the output content of the page and automatically append the parameter PHPSESSID=xxxx .

2. Common reasons why URL rewrite cannot be correctly rewrite

The output buffer is not turned on
output_add_rewrite_var depends on PHP's output buffering mechanism. If the output buffering is not enabled, the function cannot capture the output content for replacement.
The URL format is not standardized or encoding issues <br> If the URL in the page is not in a standard HTTP or HTTPS format, or has special characters, output_add_rewrite_var may not be correctly identified and processed.
Dynamically generated URLs are used in the page
Some URLs are dynamically generated or later spliced through JavaScript, and output_add_rewrite_var cannot perceive these changes when processed on the server side.
HTTP Header sent or output interrupt exists <br> If the page has sent some output before calling output_add_rewrite_var , the function may not be replaced properly.

3. Detailed solution explanation

1. Turn on and use output buffering correctly

Make sure the output buffering is enabled in the code and call output_add_rewrite_var in the appropriate location, for example:

 <?php
ob_start();
session_start();
output_add_rewrite_var('PHPSESSID', session_id());
// Page content output
echo '<a href="http://gitbox.net/path/page.php">Click to access</a>';
ob_end_flush();
?>

This ensures that the function captures the output correctly and adds parameters.

2. Manual splicing parameters as an alternative

If output_add_rewrite_var cannot meet the requirements, you can manually append parameters when generating the URL:

 <?php
session_start();
$sessionId = session_id();
echo '<a href="http://gitbox.net/path/page.php?PHPSESSID=' . urlencode($sessionId) . '">Click to access</a>';
?>

Although it is troublesome, this is the most direct and effective way.

3. Use Apache or Nginx to assist parameter passing

For situations where URL rewriting is more complicated, you can combine the server configuration to realize automatic delivery of session IDs, such as Apache's .htaccess rules:

 RewriteEngine On
RewriteCond %{QUERY_STRING} !PHPSESSID=
RewriteRule ^(.*)$ $1?PHPSESSID=%{HTTP:Cookie} [QSA,L]

This reduces dependence on the PHP level.

4. Avoid relying on output_add_rewrite_var when dynamically generating URLs in JavaScript

For dynamically generated links, you can manually append parameters during generation or pass session information through AJAX.

4. Summary

Make sure the output buffer is turned on to ensure that output_add_rewrite_var can correctly capture the page output.
The URL needs format specifications to avoid special character interference function recognition.
For dynamic URLs, avoid relying on automatic appending on server-side, and use front-end or manual splicing.
Combining server rewrite rules improves the stability of URL parameter delivery.

Only in this way can we ensure that when using output_add_rewrite_var , the URL can be correctly rewritten, the parameters are passed normally, and page function abnormality can be avoided.

output_add_rewrite_var