Tag page with Custom Post Types not returning any posts

Question

I have created a number of custom post types, but when I visit the "tag" page which should be listing those custom post types, it has no posts to show.

I created my custom post types like so:

$news_attr = array(
    'name' => 'News',
    'singluar_name' => 'News Article',
    'add_new' => 'Add News Article',
    'all_items' => 'All News Articles',
    'add_new_item' => 'Add News Article',
    'edit_item' => 'Edit News Article',
    'new_item' => 'New News Article',
    'view_item' => 'View News Article',
    'search_item' => 'Search News Articles',
    'not_found' => 'No Podcast found',
    'not_found_trash' => 'No Podcast found in Trash',
    'parent_item_colon' => 'Parent Item'
);

$news_args = array(
    'labels' => $news_attr,
    'public' => true,
    'has_archive' => true,
    'publicly_queryable' => true,
    'query_var' => true,
    'capability_type' => 'post',
    'heirarchical' => 'false',
    'supports' => array(
        'thumbnail',
        'post-thumbnails',
        'title',
        'editor',
        'excerpt',
        'revisions',
        'custom-fields',
        'author'
    ),
    'taxonomies' => array('category', 'post_tag'),
    'menu_position' => 4,
    'exclude_from_search' => false,
    'rewrite' => array('slug' => 'news-archive'),
    'menu_icon'   => 'dashicons-welcome-widgets-menus'
);

If I visit /tag/blog-articles/, it lists all the standard post-types, but none of the custom ones. How would I ensure that custom post-types are included in this?

Answer 1

WordPress, by default, shows only posts on tags and categories archives... So if you want to show your custom post type in there, then you'll have to make WordPress do that...

function add_news_articles_to_categories_and_tags( $query ) {
    if ( ! is_admin() && $query->is_main_query() && ($query->is_category || $query->is_tax ) ) {
        $query->set( 'post_type', array('post', 'news_article') ); // use your CPT slugs in here
    }
}
add_action( 'pre_get_posts', 'add_news_articles_to_categories_and_tags' );