Need to display same custom post type on 2 different singles templates

Question

I have a client who wants to display home plans (a custom post type) on their website in 2 differently branded sections, depending on which listing page the post is accessed from. I found this solution from @gmazzap from a few years ago, and it looks promising, but I can't make it work: Multiple templates for custom post type

Specifically, it fails to modify the URL on the alternate listing page: it simply uses the slug specified in the CPT registration:

'rewrite' => array( 'slug' => 'plan', 'with_front' => false ),

Which means when I click a plan link on 'page_kioskoverview,php' template it displays the post on the standard 'single-plans.php' template rather than the alternate 'single-kioskplans.php' template.

Here's what my code looks like:

add_action('template_redirect', 'change_plans_plink');
function change_plans_plink() {
  if (is_page_template('page_kioskoverview.php')) { 
    add_filter( 'post_link', 'plans_query_string', 10, 2 );
  }
}
function plans_query_string( $url, $post ) {
  if ( $post->post_type === 'plans' ) { 
    $url = add_query_arg( array('style'=>'alt'), $url );
  }
  return $url;
}

//designate alternative single template for above alt link
add_action('template_include', 'kiosk_plan_single');
function kiosk_plan_single($template) {
  if( is_singular('plans') ) {
    $alt = filter_input(INPUT_GET, 'style', FILTER_SANITIZE_STRING);
    if ( $alt === 'alt' ) $template = 'single-kioskplans.php';
  }
  return $template;
}

After a few days looking at it (and trying some variations without success), I cannot spot the problem, but I must be missing something.

Answer 1

To display different templates for the same post type I would make 2 different links, check on which link I'm currently on and decide which template to load.

Working example:

/**
 * Register event post type
 *
 * Registering event post type will add such a permalink structure event/([^/]+)/?$
 */
function wpse_288345_register_event_post_type() {

    $labels = array(
        'name' => __( 'Events' ),
        'singular_name' => __( 'Event' ),
        'add_new' => __( 'Add new' ),
        'add_new_item' => __( 'Add new' ),
        'edit_item' => __( 'Edit' ),
        'new_item' => __( 'New' ),
        'view_item' => __( 'View' ),
        'search_items' => __( 'Search' ),
        'not_found' => __( 'Not found' ),
        'not_found_in_trash' => __( 'Not found Events in trash' ),
        'parent_item_colon' => __( 'Parent' ),
        'menu_name' => __( 'Events' ),

    );

    $args = array(
        'labels' => $labels,
        'hierarchical' => false,
        'supports' => array( 'title', 'page-attributes' ),
        'taxonomies' => array(),
        'public' => true,
        'show_ui' => true,
        'show_in_menu' => true,
        'show_in_nav_menus' => false,
        'publicly_queryable' => true,
        'exclude_from_search' => false,
        'has_archive' => true,
        'query_var' => true,
        'can_export' => true,
        'rewrite' => array('slug' => 'event'),
        'capability_type' => 'post',
    );

    register_post_type( 'event', $args );
}

add_action( 'init', 'wpse_288345_register_event_post_type' );

/**
 * Add custom rewrite rule for event post type.
 *
 * Remember to flush rewrite rules to apply changes.
 */
function wpse_288345_add_event_rewrite_rules() {

    /**
     * Custom rewrite rules for one post type.
     * 
     * We wil know on which url we are by $_GET parameters 'performers' and 'summary'. Which we will add to
     * public query vars to obtain them in convinient way.
     */
    add_rewrite_rule('event/performers/([^/]+)/?$', 'index.php?post_type=event&name=$matches[1]&performers=1', 'top');
    add_rewrite_rule('event/summary/([^/]+)/?$', 'index.php?post_type=event&name=$matches[1]&summary=1', 'top');
}

add_action('init', 'wpse_288345_add_event_rewrite_rules');

/**
 * Add 'performers' and 'summary' custom event query vars.
 */
function wpse_288345_register_event_query_vars( $vars ) {

    $vars[] = 'performers';
    $vars[] = 'summary';

    return $vars;
}

add_filter( 'query_vars', 'wpse_288345_register_event_query_vars' );

/**
 * Decide which template to load
 */
function wpse_288345_load_performers_or_summary_template( $template ) {

    // Get public query vars
    $performers = (int) get_query_var( 'performers', 0 );
    $summary    = (int) get_query_var( 'summary', 0 );

    // If performer = 1 then we are on event/performers link
    if( $performers === 1 ) {
        $template = locate_template( array( 'single-event-performers.php' ) );
    }

    // If summary = 1 then we are on event/summary link
    if( $summary === 1 ) {
        $template = locate_template( array( 'single-event-summary.php' ) );
    }

    if($template == '') {
        throw new \Exception('No template found');
    }

    return $template;
}

add_filter( 'template_include', 'wpse_288345_load_performers_or_summary_template' );

Answer 2

Here's the alternative approach that I made work, using a GET parameter and conditional statements.

1. On the alternate listing page, I added '?template=kiosk' to the permalinks.

2. On the singles template (single-plans.php) I added the following to the top of the template (and of course 'endif' at bottom of template):

   $kiosk = $_GET['template'];
   if(isset($kiosk)) :

3. Then, throughout the template, I created conditional statements based on whether or not there was a parameter, to display content appropriately:

   if(isset($kiosk)) { 
       show kiosk version
       } else {
       show standard version
       }

Answer 3

I was trying almost the exactly the same code too, and it wasn't working. There's just one change to make for this to operate completely. Just add locate_template to one line.

Change

if ( $alt === 'alt' ) $template = 'single-kioskplans.php';

to

if ( $alt === 'alt' ) $template = locate_template('single-kioskplans.php');

The full code will look like this:

add_action('template_redirect', 'change_plans_plink');
function change_plans_plink() {
  if (is_page_template('page_kioskoverview.php')) { 
    add_filter( 'post_link', 'plans_query_string', 10, 2 );
  }
}
function plans_query_string( $url, $post ) {
  if ( $post->post_type === 'plans' ) { 
    $url = add_query_arg( array('style'=>'alt'), $url );
  }
  return $url;
}

//designate alternative single template for above alt link
add_action('template_include', 'kiosk_plan_single');
function kiosk_plan_single($template) {
  if( is_singular('plans') ) {
    $alt = filter_input(INPUT_GET, 'style', FILTER_SANITIZE_STRING);
    if ( $alt === 'alt' ) $template = locate_template('single-kioskplans.php');
  }
  return $template;
}