Wordpress yoast seo plugin, generate custom sitemap for custom URLS

yoast-seo-sitemap.php

<?php
/**
 *  Create a new custom yoast seo sitemap
 */
 
add_filter( 'wpseo_sitemap_index', 'ex_add_sitemap_custom_items' );
add_action( 'init', 'init_wpseo_do_sitemap_actions' );


// Add custom index
function ex_add_sitemap_custom_items(){
	global $wpseo_sitemaps;
	$date = $wpseo_sitemaps->get_last_modified('CUSTOM_POST_TYPE');

	$smp ='';

    	$smp .= '<sitemap>' . "\n";
	$smp .= '<loc>' . site_url() .'/CUSTOM_KEY-sitemap.xml</loc>' . "\n";
	$smp .= '<lastmod>' . htmlspecialchars( $date ) . '</lastmod>' . "\n";
	$smp .= '</sitemap>' . "\n";


	return $smp;
}


function init_wpseo_do_sitemap_actions(){
	add_action( "wpseo_do_sitemap_CUSTOM_KEY", 'ex_generate_origin_combo_sitemap');
}




function ex_generate_origin_combo_sitemap(){


	global $wpdb;
	global $wp_query;
	global $wpseo_sitemaps;

        $post_type = 'CUSTOM_POST_TYPE';

	wp_reset_query();
	$args = array(
		'posts_per_page'   => -1,
		'orderby'          => 'post_date',
		'order'            => 'DESC',
		'post_type'        => $post_type,
		'post_status'      => 'publish',
		'suppress_filters' => true
	);
	query_posts( $args );
	wp_reset_postdata();

	//echo '<pre>';print_r($url);echo '</pre>';
	$posts_array = get_posts( $args );

	$output = '';
	if( !empty( $posts_array ) ){

		$chf = 'weekly';
		$pri = 1.0;

		foreach ( $posts_array as $p ) {
			$p->post_type   = $post_type;
			$p->post_status = 'publish';
			$p->filter      = 'sample';



			$url = array();

			if ( isset( $p->post_modified_gmt ) && $p->post_modified_gmt != '0000-00-00 00:00:00' && $p->post_modified_gmt > $p->post_date_gmt ) {
				$url['mod'] = $p->post_modified_gmt;
			} else {
				if ( '0000-00-00 00:00:00' != $p->post_date_gmt ) {
					$url['mod'] = $p->post_date_gmt;
				} else {
					$url['mod'] = $p->post_date;
				}
			}

			$url['loc'] = site_url().'/sample/all/'.$p->post_name;
			$url['chf'] = $chf;
			$url['pri'] = $pri;


			$output .= $wpseo_sitemaps->sitemap_url( $url );

			// Clear the post_meta and the term cache for the post, as we no longer need it now.
			// wp_cache_delete( $p->ID, 'post_meta' );
			// clean_object_term_cache( $p->ID, $post_type );
		}
	}

	// Grab last modified date
	$sql  = $wpdb->prepare(" SELECT MAX(p.post_modified_gmt) AS lastmod
		FROM	$wpdb->posts AS p
		WHERE post_status IN ('publish') AND post_type = %s ", $post_type );

	$mod = $wpdb->get_var( $sql );

	// Generate terms URLs
	$practitioner_terms = get_terms( 'TAXONOMY', 'orderby=count&hide_empty=0' );
	if( !empty( $practitioner_terms ) ){

		$pri = 1;
		$chf = 'weekly';

		foreach ($practitioner_terms as $key => $term ){

			$url = array();

			$url['loc'] = site_url().'/sample/'.$term->slug;
		      	$url['pri'] = $pri;
		      	$url['mod'] = $mod;
		      	$url['chf'] = $chf;
		      	$output .= $wpseo_sitemaps->sitemap_url( $url );

		}
	}

	// Generate permutation & combinations
	if( ( !empty( $practitioner_terms) ) &&  ( ! empty($posts_array ) ) ){

		$pri = 1;
		$chf = 'weekly';

		wp_reset_postdata();


		foreach ($practitioner_terms as $key => $term ){

			$args = array(
				'posts_per_page'   => -1,
				'orderby'          => 'post_date',
				'order'            => 'DESC',
				'post_type'        => $post_type,
				'post_status'      => 'publish',
				'suppress_filters' => true,
				'tax_query' => array(
				    array(
				        'taxonomy' => 'TAXONOMY',
				        'field'    => 'slug',
				        'terms'    => $term->slug,
				        'operator' => 'IN'
				    ),
				),
			);

			$posts_array = get_posts( $args );
			//echo '<pre>';print_r($posts_array);echo '</pre>';

			$url = array();

			foreach ($posts_array as $key => $p ){
				$url['loc'] = site_url().'/sample/'.$term->slug.'/'.$p->post_name;
			      	$url['pri'] = $pri;
			      	$url['mod'] = $mod;
			      	$url['chf'] = $chf;
			      	$output .= $wpseo_sitemaps->sitemap_url( $url );

			}

		}
	}


        if ( empty( $output ) ) {
            $wpseo_sitemaps->bad_sitemap = true;
            return;
        }

        //Build the full sitemap
        $sitemap = '<urlset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" ';
        $sitemap .= 'xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9 http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd" ';
        $sitemap .= 'xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">' . "\n";
        $sitemap .= $output . '</urlset>';

        //echo $sitemap;
        $wpseo_sitemaps->set_sitemap($sitemap);

}

/*********************************************************
 *  OR we can use $wpseo_sitemaps->register_sitemap( 'CUSTOM_KEY', 'METHOD' );
 ********************************************************/

add_action( 'init', 'ex_register_my_new_sitemap', 99 );
/**
 * On init, run the function that will register our new sitemap as well
 * as the function that will be used to generate the XML. This creates an
 * action that we can hook into built around the new
 * sitemap name - 'wp_seo_do_sitemap_my_new_sitemap'
 */
function ex_register_my_new_sitemap() {
	global $wpseo_sitemaps;
	$wpseo_sitemaps->register_sitemap( 'CUSTOM_KEY', 'ex_generate_origin_combo_sitemap' );
}

add_action( 'init', 'init_do_sitemap_actions' );

function init_do_sitemap_actions(){
	add_action( 'wp_seo_do_sitemap_our-CUSTOM_KEY', 'ex_generate_origin_combo_sitemap' );
}

In the filter, you want to "add" instead of overwriting right now. Otherwise if you do this multiple times, you'll just have the latest sitemap function that ran. So you'd want these changes to add multiple sitemap indexes :

-function ex_add_sitemap_custom_items(){
+function ex_add_sitemap_custom_items($smp){
	global $wpseo_sitemaps;
	$date = $wpseo_sitemaps->get_last_modified('CUSTOM_POST_TYPE');

-	$smp ='';

    	$smp .= '<sitemap>' . "\n";

Why is ex_generate_origin_combo_sitemap() assigned to two different hooks AND register_sitemap()? Shouldn't register_sitemap() alone suffice? Is this a backwards compatibility thing?

Thanks for the snippet. Modifying it a bit to adapt it to the latest Yoast version works like a charm. :)

Why is ex_generate_origin_combo_sitemap() assigned to two different hooks AND register_sitemap()? Shouldn't register_sitemap() alone suffice? Is this a backwards compatibility thing?

Yes - only register_sitemap() is required. Lines like add_action( "wpseo_do_sitemap_CUSTOM_KEY", '....'); are redundant as register_sitemap() already adds these actions, see line 165 of the Yoast source class.

Just added two new gists as a more comprehensive examples. All in one file, including writing sitemap <url> tags with images. Don't have all the extra "practitioner" cruft.

Sitemap without a data source specified:
https://gist.github.com/leepowers/2b32f734571cbeadc811b93501cfcced

Sitemap sourced from post type(s):
https://gist.github.com/leepowers/946d9c72e06779acbb2a125e5b53f475

Exactly what I was looking for, thanks!

I am getting 404 - page not found in my staging environment after generating custom sitemap using this code. Please suggest a fix for this. I have already saved permalink, cleared all kind of cache but still not working.