WordPress Rewrite API Examples

.htaccess

<IfModule mod_rewrite.c>
    # enable rewriting
    RewriteEngine on

    # don't rewrite files that exist in the file system
    RewriteCond %{REQUEST_FILENAME} !-f

    # don't rewrite directories that exist in the file system
    RewriteCond %{REQUEST_FILENAME} !-d

    # rewrite the request to index.php
    RewriteRule ^ index.php [QSA,L]
</IfModule>

index.php

<?php

/**
 * Process a requested URI into a simple response
 */
// requested URI
$request = trim( $_SERVER['REQUEST_URI'], '/' );

// default response
$response = '--- not found';

// a empty array in which to parse query strings
$query_vars = [];

// see if the requested uri matches the pattern for a single post
$query = preg_replace_callback(

  // the regex pattern to be matched
  '#post/(.*)#',

  // the callback that fires if the regex is matched
  function( $matches ){

    // a query-like string with key-value pairs.
    return "post=$matches[1]";
  },

  // the requested URI
  $request );

// parse the query string into the array
parse_str( $query, $query_vars );

// respond to the request for a single post
if ( isset( $query_vars['post'] ) ){
  $response = "Well hellooooooo!  You've reached the post with the slug: {$query_vars['post']}";
}

print $response;

rewrite-endpoint-debug.php

<?php

add_action( 'init', 'debug_endpoint_init' );
add_action( 'loop_start', 'debug_endpoint_loop_start' );

/**
 * Add our new debug endpoint
 */
function debug_endpoint_init(){
	add_rewrite_endpoint( 'debug', EP_ALL );
}

/**
 * Respond to our new endpoint
 */
function debug_endpoint_loop_start(){
	// main query only
	if ( !is_main_query() ) {
		return;
	}

	$debug = get_query_var( 'debug' );

	// look for a debug query variable that has a value
	if ( !empty( $debug ) ) {

		// show post information if on a permalink
		if ( $debug == 'post' ){
			$post = get_post();
			d( $post );
		}

		// show wp_query info if debug has value of "query"
		if ( $debug == 'query' ) {
			global $wp_query;
			d( $wp_query );
		}
	}
}

rewrite-endpoint-json.php

<?php

add_action( 'init', 'json_endpoint_init' );
add_action( 'template_include', 'json_endpoint_template_include' );

/**
 * Add our new json endpoint
 */
function json_endpoint_init(){
	add_rewrite_endpoint( 'json', EP_PERMALINK | EP_PAGES );
}

/**
 * Respond to our new endpoint
 *
 * @param $template
 *
 * @return mixed
 */
function json_endpoint_template_include( $template ){

	global $wp_query;

	// since the "json" query variable does not require a value, we need to
	// check for its existence
	if ( is_singular() && isset( $wp_query->query_vars['json'] ) ) {
		$post = get_post();

		wp_send_json( (array) $post );
	}

	return $template;
}

rewrite-rule-example.php

<?php
add_action('init', 'rewrite_rule_example');

/**
 * Add rewrite rule for a pattern matching "post-by-slug/<post_name>"
 */
function rewrite_rule_example() {
	add_rewrite_rule('^post-by-slug/(.*)/?', 'index.php?name=$matches[1]', 'top');
}

rewrite-tag-example.php

<?php

add_action( 'init', 'rewrite_tag_example_init' );
add_action( 'template_redirect', 'rewrite_tag_example_template_redirect' );

/**
 * Add rewrite rule and tag to WP
 */
function rewrite_tag_example_init(){
	// rewrite tag adds the matches found in the pattern to the global $wp_query
	add_rewrite_tag( '%affiliate%', '(.*)' );
}

/**
 * Modify the query based on our rewrite tag
 */
function rewrite_tag_example_template_redirect(){

	// get the value of our rewrite tag
	$affiliate = get_query_var( 'affiliate' );

	// check if our rewrite tag has value
	if ( !empty( $affiliate ) ){

		// track where this visitor came from
		setcookie( 'affiliate', $affiliate, 0, '/' );
	}
}

rewrite-tag-permalink.php

<?php

add_action( 'init', 'rewrite_tag_permalink_init' );
add_action( 'pre_get_posts', 'rewrite_tag_permalink_pre_get_posts' );

// normal posts
add_filter( 'post_link', 'rewrite_tag_permalink_post_link', 10, 2 );
// custom post types
add_filter( 'post_type_link', 'rewrite_tag_permalink_post_link', 10, 2 );

/**
 * Add our rewrite rule and rewrite tag
 */
function rewrite_tag_permalink_init(){
	// rewrite rule looks for custom_folder
	add_rewrite_rule( '^([^/]+)/(.*)/?', 'index.php?custom_folder=$matches[1]&name=$matches[2]', 'bottom' );

	// rewrite tag puts custom_folder value into the query vars
	add_rewrite_tag( '%custom_folder%', '(.*)' );
}

/**
 * Alter permalinks to reflect the new custom_folder rewrite tag
 *
 * @param $permalink
 * @param $post
 *
 * @return mixed
 */
function rewrite_tag_permalink_post_link( $permalink, $post ) {
	$rewrite_tag = '%custom_folder%';

	// return early if tag not found
	if ( strpos( $permalink, $rewrite_tag ) === FALSE ) {
		return $permalink;
	}

	// look for custom permalink meta data
	$custom_folder = get_post_meta( $post->ID, 'custom_folder', true );

	// if a custom permalink exists as meta data, use it
	if ( !empty( $custom_folder ) ){
		$permalink = str_replace( $rewrite_tag, $custom_folder, $permalink );
	}
	// fallback by completely removing our tag from the permalink
	else {
		$permalink = str_replace( $rewrite_tag . '/', '', $permalink );
	}

	return $permalink;
}

/**
 * Use pre_get_posts to make the custom_folder meta data value  optional
 *
 * @param $query
 */
function rewrite_tag_permalink_pre_get_posts( $query ){
	if ( $query->is_main_query() ){

		// if only the first argument is presented, use it as the post name
		if ( get_query_var( 'custom_folder' ) &&
		     !get_query_var( 'name' ) )
		{
			// what we thought was the custom_folder is actually the post_name
			$query->set( 'name', get_query_var( 'custom_folder' ) );
			$query->is_home = false;
			$query->is_singular = true;
			$query->is_single = true;
		}
	}
}

url-longerer.php

<?php

add_action( 'init', 'url_longerer_init' );
add_action( 'template_redirect', 'url_longerer_template_redirect' );

/**
 * Add rewrite rule and tag to WP
 */
function url_longerer_init(){
	// rewrite rule tells wordpress to expect the given url pattern
	add_rewrite_rule( '^longerer/(.*)/?', 'index.php?longerer=$matches[1]', 'top' );

	// rewrite tag adds the matches found in the pattern to the global $wp_query
	add_rewrite_tag( '%longerer%', '(.*)' );
}

/**
 * Modify the query based on our rewrite tag
 */
function url_longerer_template_redirect(){
	
	// get the value of our rewrite tag
	$longerer = get_query_var( 'longerer' );
	
	// look for the existence of our rewrite tag
	if ( get_query_var( 'longerer' ) ){

		// get the post ID from the longerer string
		$post_ID = url_longerer_decode_in_some_way( $longerer );

		// attempt to find the permalink associated with this post ID
		$permalink =  get_permalink( $post_ID );

		// if valid, send to permalink
		if ( $post_ID && $permalink ){
			wp_redirect( $permalink );
		}
		// otherwise, send to homepage
		else {
			wp_redirect( home_url() );
		}
		exit;
	}
}