README

A class to copy into your WordPress plugin, to allow loading template parts with fallback through the child theme > parent theme > plugin.

Description

Easy Digital Downloads, WooCommerce, and Events Calendar plugins, amongst others, allow you to add files to your theme to override the default templates that come with the plugin. As a developer, adding this convenience in to your own plugin can be a little tricky.

The get_template_part() function in WordPress was never really designed with plugins in mind, since it relies on locate_template() which only checks child and parent themes. So we can add in a final fallback that uses the templates in the plugin, we have to use a custom locate_template() function, and a custom get_template_part() function. The solution here just wraps them up as a class for convenience.

Installation

This isn't a WordPress plugin on its own, so the usual instructions don't apply. Instead:

Manually install class

1. Copy class-gamajo-template-loader.php into your plugin. It can be into a file in the plugin root, or better, an includes directory.

or:

Install class via Composer

1. Tell Composer to install this class as a dependency: composer require gamajo/template-loader
2. Recommended: Install the Mozart package: composer require coenjacobs/mozart --dev and configure it.
3. The class is now renamed to use your own prefix, to prevent collisions with other plugins bundling this class.

Implement class

1. Create a new file, such as class-your-plugin-template-loader.php, in the same directory.
2. Create a class in that file that extends Gamajo_Template_Loader (or the new prefixed name, if you installed via Composer/Mozart). You can see the Meal Planner Template Loader example class below as a starting point if it helps.
3. Override the class properties to suit your plugin. You could also override the get_templates_dir() method if it isn't right for you.
4. You can now instantiate your custom template loader class, and use it to call the get_template_part() method. This could be within a shortcode callback, or something you want theme developers to include in their files.

// Template loader instantiated elsewhere, such as the main plugin file. $meal_planner_template_loader = new Meal_Planner_Template_Loader();

• Use it to call the get_template_part() method. This could be within a shortcode callback, or something you want theme developers to include in their files.

  $meal_planner_template_loader->get_template_part( 'recipe' );

• If you want to pass data to the template, call the set_template_data() method with an array before calling get_template_part(). set_template_data() returns the loader object to allow for method chaining.

  $data = array( 'foo' => 'bar', 'baz' => 'boom' ); $meal_planner_template_loader ->set_template_data( $data ) ->get_template_part( 'recipe' );

  The value of bar is now available inside the recipe template as $data->foo.

  If you wish to use a different variable name, add a second parameter to set_template_data():

  $data = array( 'foo' => 'bar', 'baz' => 'boom' ); $meal_planner_template_loader ->set_template_data( $data, 'context' ) ->get_template_part( 'recipe', 'ingredients' );

  The value of bar is now available inside the recipe template as $context->foo.

  This will try to load up wp-content/themes/my-theme/meal-planner/recipe-ingredients.php, or wp-content/themes/my-theme/meal-planner/recipe.php, then fallback to wp-content/plugins/meal-planner/templates/recipe-ingredients.php or wp-content/plugins/meal-planner/templates/recipe.php.

• You can also pass the template loader object into the template as well:

  $template_loader = new Your_Template_Loader(); $template_loader->set_template_data( array( 'template_loader' => $template_loader, // Optional other data as needed. ) );

  Then in the template you can use:

  $data->template_loader->get_template_part( 'recipe' );

Meal Planner Example Class

<?php /**  * Meal Planner  *  * @package Meal_Planner  * @author Gary Jones  * @link http://example.com/meal-planner  * @copyright 2013 Gary Jones  * @license GPL-2.0+  */ if ( ! class_exists( 'Gamajo_Template_Loader' ) ) { require plugin_dir_path( __FILE__ ) . 'class-gamajo-template-loader.php'; } /**  * Template loader for Meal Planner.  *  * Only need to specify class properties here.  *  * @package Meal_Planner  * @author Gary Jones  */ class Meal_Planner_Template_Loader extends Gamajo_Template_Loader { /**  * Prefix for filter names.  *  * @since 1.0.0  *  * @var string  */ protected $filter_prefix = 'meal_planner'; /**  * Directory name where custom templates for this plugin should be found in the theme.  *  * @since 1.0.0  *  * @var string  */ protected $theme_template_directory = 'meal-planner'; /**  * Reference to the root directory path of this plugin.  *  * Can either be a defined constant, or a relative reference from where the subclass lives.  *  * In this case, `MEAL_PLANNER_PLUGIN_DIR` would be defined in the root plugin file as:  *  * ~~~  * define( 'MEAL_PLANNER_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );  * ~~~  *  * @since 1.0.0  *  * @var string  */ protected $plugin_directory = MEAL_PLANNER_PLUGIN_DIR; /**  * Directory name where templates are found in this plugin.  *  * Can either be a defined constant, or a relative reference from where the subclass lives.  *  * e.g. 'templates' or 'includes/templates', etc.  *  * @since 1.1.0  *  * @var string  */ protected $plugin_template_directory = 'templates'; }

Usage Example

The Cue plugin from AudioTheme uses this class. Starting at https://github.com/AudioTheme/cue/tree/develop/includes, it has this class in the vendor directory, then the required subclass of my class in the class-cue-template-loader.php file, which sets a few basic properties. It also has a template in https://github.com/AudioTheme/cue/tree/develop/templates.

If you wanted the playlist to have different markup for your theme, you'd copy templates/playlist.php to wp-content/themes/{your-active-theme}/cue/playlist.php and do whatever changes you wanted. WordPress will look for that file first, before then checking a parent theme location (if your active theme is a child theme), before falling back to the default template that comes with the Cue plugin.

Change Log

See the change log.

License

GPL 2.0 or later.

Contributions

Contributions are welcome - fork, fix and send pull requests against the develop branch please.

Credits

Built by Gary Jones
Copyright 2013 Gary Jones