[WordPress - Programmatically Assign Page Template to CPT Posts] #wp #core #cpt #custom #post #types #page #templates

wp--attach-template-to-cpt-posts.php

/**
 * Attaches the specified template to the posts of the identified post type.
 *
 * @params    $post_type        The name of the post type to attach the template to.
 * @params    $template_path    The template's filename (assumes .php' is specified)
 *
 * @returns   empty array if the post type does not have posts; otherwise, 
 *            the post id array of the updated posts.
 */
function attach_template_to_post_type( $post_type, $template_file_name ) {

	$posts_args_Arr = array(
		'post_type' 		=> $post_type,
		'posts_per_page' 	=> -1,
	);

	$posts_Arr 			= get_posts($posts_args_Arr);
	$updated_posts_Arr 	= [];

	if ( 0 < count($posts_Arr) ) :

		foreach ( $posts_Arr as $post ) : setup_postdata( $post );

			if (
					isset($post->ID) 		&&
					is_numeric($post->ID) 	&&
					0 < intval($post->ID)
				) :
				
				update_post_meta( $post->ID, '_wp_page_template', $template_file_name );
				array_push($updated_posts_Arr, $post->ID);	

			endif;

		endforeach;

		wp_reset_postdata();

	endif;
  
    return $updated_posts_Arr;
 
}

// Usage - just put it in functions.php. You can't use hooks here since you need to
// 		   use specific function parameters.
attach_template_to_post_type( 'mac-city-pages', 'page-landing.php' );