Create Custom Post type that uses Page.php template

Question

I am creating a plugin that registers a custom post type, and I want it to be displayed using the theme's page.php template, rather than the post.php. I set the hierarchical flag when I register it, but the post.php template is still called.

Way, way down inside wp-includes/post.php, where it appears to decide which template to use, is the code:

if ( ! empty( $postarr['page_template'] ) && 'page' == $data['post_type'] ) {
    $post->page_template = $postarr['page_template'];
    $page_templates = wp_get_theme()->get_page_templates( $post );
    ...

which makes me think that the post template is used unless post_type is exactly 'page'.

I don't want to define a template of my own, because I want to work with any theme. I just want to tell WordPress which of the current theme's templates to use.

There's an action hook, called get_template_part_{$slug} that might do the trick, but I'm not sure what it expects, and the documentation for that one is unusually spotty.

Answer 1

You can filter template_include and then let WordPress search for a page template in all valid templates like page.php, index.php and even files from a parent theme.

add_filter( 'template_include', function( $template ) {
    return is_singular( [ 'YOUR_POST_TYPE' ] ) ? get_page_template() : $template;
});

Answer 2

That's exactly it. You should be able to use something like this, replacing the your_post_type:

function get_custom_post_type_template($single_template) {
    global $post;

    if ($post->post_type == 'your_post_type') {
        $single_template = get_stylesheet_directory_uri() . '/page.php';
    }
    return $single_template;
}
add_filter( 'single_template', 'get_custom_post_type_template' );