Title: [Plugin/Hack: Piggyback Rewrite Rule]
Last modified: August 19, 2016

---

# [Plugin/Hack: Piggyback Rewrite Rule]

 *  [k4st](https://wordpress.org/support/users/k4st/)
 * (@k4st)
 * [18 years ago](https://wordpress.org/support/topic/pluginhack-piggyback-rewrite-rule/)
 * Sometimes it’s nice to just be able to force a pattern into the wordpress rewrite
   class and the database. This plugin will get that done for you. Enjoy.
 *     ```
       <?php
       /*
       Plugin Name: Piggyback Rewrite Rules
       Plugin URI: http://ioreader.com
       Description: Force rewrite rules into the database and the WP_Rewrite class.
       Author: Peter Goodman
       */
   
       // yikes!
       !defined('WP_MAIN_DIR') &&
           define('WP_MAIN_DIR', dirname(dirname(dirname(__FILE__))));
   
       /**
        * Piggyback a rule into the WP_Rewrite class, even if it doesn't exist in the
        * database (yet). Note: do not anchor regular expression rules to the start of
        * a subject. Anchor them to the end of one, ie: regex here $. Do not put any
        * delimiters or modifiers in the regular expression. When accessing subpattern
        * matches in $location, use: $matches[x] where 'x' is the numbered subpattern.
        * The first subpattern can be referenced by $matches[1].
        * @author Peter Goodman
        */
       function piggyback_rewrite_rule($regex = '', $location = '') {
           static $rules = array();
   
           if(!empty($regex)) {
               $rules[$regex] = $location;
               return;
           }
   
           return $rules;
       }
   
       /**
        * Add in the piggybacked rules.
        * @author Peter Goodman
        * @internal
        */
       function piggyback_rewrite_rules() {
           global $wp_rewrite;
   
           // this has likely been cached already
           $rules =& get_option('rewrite_rules');
           $changed = FALSE;
           $force = FALSE; // for debugging
   
           // go over the piggybacked rules and add them in if necessary
           foreach(piggyback_rewrite_rule() as $regex => $location) {
   
               // make sure it gets into the database
               if(!isset($rules[$regex]) || $force) {
                   $rules[$regex] = $location;
                   $changed = TRUE;
               }
   
               // make sure it shows up in the class as well, this is less important
               // we put it into the extra_rules as well to make sure it will live on
               // if we rewrite the rules.
               $wp_rewrite->rules[$regex] = $location;
               $wp_rewrite->extra_rules[$regex] = $location;
           }
   
           // update the db options
           if($changed || $force) {
   
               // discard any changed (and no longer useful) rules that no longer
               // need to be in the database
               $wp_rewrite->rewrite_rules();
               krsort($wp_rewrite->rules);
               update_option('rewrite_rules', $wp_rewrite->rules);
   
               // if .htaccess doesn't exist for some reason, create it.
               $htaccess = WP_MAIN_DIR .'/.htaccess';
               if(!file_exists($htaccess))
                   piggyback_force_rewrite($htaccess);
           }
       }
   
       /**
        * Force a rewrite of the .htaccess file if it doesn't yet exist.
        * @author Peter Goodman
        * @internal
        */
       function piggyback_force_rewrite($htaccess_file) {
           global $wp_rewrite;
   
           $rules = $wp_rewrite->mod_rewrite_rules();
           $fp = fopen($htaccess_file, "w");
   
           // write the rules to the .htaccess
           if(is_resource($fp)) {
               fwrite($fp, $rules);
               fclose($fp);
           }
       }
   
       // could use add_action, but it just calls add_filter and so we will ignore
       // the distinction. The priority is 1 so that it is executed *before* the
       // redirect_canonical() function
       add_filter('template_redirect', 'piggyback_rewrite_rules', 1);
   
       /**
        * Helper function for doing feeds.
        */
       function rewrite_feed($extra = '') {
           return 'index.php?&feed=$matches[1]' . $extra;
       }
       ```
   

The topic ‘[Plugin/Hack: Piggyback Rewrite Rule]’ is closed to new replies.

## Tags

 * [apache](https://wordpress.org/support/topic-tag/apache/)
 * [htaccess](https://wordpress.org/support/topic-tag/htaccess/)
 * [mod_rewrite](https://wordpress.org/support/topic-tag/mod_rewrite/)
 * [rule](https://wordpress.org/support/topic-tag/rule/)

 * 0 replies
 * 1 participant
 * Last reply from: [k4st](https://wordpress.org/support/users/k4st/)
 * Last activity: [18 years ago](https://wordpress.org/support/topic/pluginhack-piggyback-rewrite-rule/)
 * Status: not a support question

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