In a nutshell what I want to achieve is this:

If slug equals foobar serve the foobar.php template.

I know I could do this with page-foobar.php but I don't want to create a page for this.

add_action('init', 'template_suggestions');
function template_suggestions() {

  global $wp;

  $current_slug = add_query_arg([], $wp->request);

  if ($current_slug == 'foobar') {

    // No, don't server the 404.php.
    // Serve foobar.php.
    // But how?
    // Big question mark.
  }
}

In a nutshell what I want to achieve is this:

If slug equals foobar serve the foobar.php template.

I know I could do this with page-foobar.php but I don't want to create a page for this.

add_action('init', 'template_suggestions');
function template_suggestions() {

  global $wp;

  $current_slug = add_query_arg([], $wp->request);

  if ($current_slug == 'foobar') {

    // No, don't server the 404.php.
    // Serve foobar.php.
    // But how?
    // Big question mark.
  }
}

• templates

1 Answer 1

Got it! But this is a dirty thing. As it won't take care of pagination and underlying queries. If you need a bit more of WordPress' logic behind that custom route, please check the answer linked in the comments. But if you just need to serve one static page, this probably is a good starting point:

add_action('template_include', 'template_suggestions');
function template_suggestions($template) {

  global $wp;

  $current_slug = $wp->request;

  $foobar_template = locate_template(['foobar.php']);

  if ($current_slug == 'foobar' && $foobar_template != '') {

    // Prevent 404.
    status_header(200);

    return $foobar_template;
  }

  return $template;
}

Source Don’t use template_redirect to load an alternative template file

Since I use Yoast I had to use wpseo_title instead of document_title_parts or pre_get_document_title to set the title accordingly.

add_filter('wpseo_title', 'template_suggestions_titles', 10, 1);
function template_suggestions_titles() {

  global $wp;

  $current_slug = $wp->request;

  if ($current_slug == 'foobar') {

    return 'Foobar';
  }
}