Creating a wordpress plugin where users can override templates

1 comment

1. You have to write it yourself. Check out the way WP e-commerce does it:

   First, the function to “register” the theme files.

   function wpsc_register_theme_file( $file_name ) {
       global $wpec_theme_files;
   
       if ( !in_array( $file_name, (array)$wpec_theme_files ) )
           $wpec_theme_files[] = $file_name;
   }
   

   And then the function to find a theme file:

   /**
    * Checks the active theme folder for the particular file, if it exists then return the active theme directory otherwise
    * return the global wpsc_theme_path
    * @access public
    *
    * @since 3.8
    * @param $file string filename
    * @return PATH to the file
    */
    function wpsc_get_template_file_path( $file = '' ){
   
        // If we're not looking for a file, do not proceed
        if ( empty( $file ) )
            return;
   
        // No cache, so find one and set it
        if ( false === ( $file_path = get_transient( WPEC_TRANSIENT_THEME_PATH_PREFIX . $file ) ) ) {
            // Look for file in stylesheet
            if ( file_exists( get_stylesheet_directory() . '/' . $file ) ) {
                $file_path = get_stylesheet_directory() . '/' . $file;
   
            // Look for file in template
            } elseif ( file_exists( get_template_directory() . '/' . $file ) ) {
                $file_path = get_template_directory() . '/' . $file;
   
            // Backwards compatibility
            } else {
                // Look in old theme path
                $selected_theme_check = WPSC_OLD_THEMES_PATH . get_option( 'wpsc_selected_theme' ) . '/' . str_ireplace( 'wpsc-', '', $file );
   
                // Check the selected theme
                if ( file_exists( $selected_theme_check ) ) {
                    $file_path = $selected_theme_check;
   
                // Use the bundled file
                } else {
                    $file_path = WPSC_CORE_THEME_PATH . '/' . $file;
                }
            }
            // Save the transient and update it every 12 hours
            if ( !empty( $file_path ) )
                set_transient( WPEC_TRANSIENT_THEME_PATH_PREFIX . $file, $file_path, 60 * 60 * 12 );
   
        }elseif(!file_exists($file_path)){
            delete_transient(WPEC_TRANSIENT_THEME_PATH_PREFIX . $file);
            wpsc_get_template_file_path($file);
        }
   
        // Return filtered result
        return apply_filters( WPEC_TRANSIENT_THEME_PATH_PREFIX . $file, $file_path );
    }
   

   In an init hook, the plugin registers all the theme files that it needs using wpsc_register_theme_file():

   wpsc_register_theme_file( 'wpsc-single_product.php' );
   wpsc_register_theme_file( 'wpsc-grid_view.php' );
   wpsc_register_theme_file( 'wpsc-list_view.php' );
   wpsc_register_theme_file( 'wpsc-products_page.php' );
   wpsc_register_theme_file( 'wpsc-shopping_cart_page.php' );
   wpsc_register_theme_file( 'wpsc-transaction_results.php' );
   wpsc_register_theme_file( 'wpsc-user-log.php' );
   wpsc_register_theme_file( 'wpsc-cart_widget.php' );
   wpsc_register_theme_file( 'wpsc-featured_product.php' );
   wpsc_register_theme_file( 'wpsc-category-list.php' );
   wpsc_register_theme_file( 'wpsc-category_widget.php' ); 
   

   And then when the file is actually needed, they call wpsc_get_template_file_path():

   switch ( $display_type ) {
           case "grid":
               include( wpsc_get_template_file_path( 'wpsc-grid_view.php' ) );
               break; // only break if we have the function;
   
           case "list":
               include( wpsc_get_template_file_path( 'wpsc-list_view.php' ) );
               break; // only break if we have the file;
           default:
               include( wpsc_get_template_file_path( 'wpsc-products_page.php' ) );
               break;
       }
   

   Obviously the code would look different for your plugin, but the principles should be the same.

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