Adding support for automatic upgrades to your WordPress plugins is really simple. After you have setup your product in the Downloads section and check enable license creation, there is just a small code snippet and two files that you need to include in your WordPress plugin.

There are three components to the updater:

1. The EDD_SL_Plugin_Updater.php file. This contains the class that makes the magic happen.
2. The extendd-settings.php handles the settings page.
3. The code snippet that you place somewhere in your plugin that loads the updater provided by the EDD_SL_PLugin_Updater.php class file.

Step 1 – Define the Updater Variables in OOP class

OOP

What ever your class may be, set up some private vars:

class my_custom_plugin_class {
        var $version;

	private $plugin_id,
		$plugin_name;

And set those variables in the constructor or your init function:

function __construct() {
		$this->version		= '1.1.6';
		$this->plugin_name	= 'Custom Login Pro';
		$this->plugin_id	= 'wp_custom_login_pro'; // Always prefix the plugin_id with "wp_"!

Step 2 – Include the Classes

The update system itself is contained within the file called EDD_SL_Plugin_Updater.php and the settings is included in the file extendd-settings.php. You need to include these files in your main plugin file, like so:

/**
 * Upgrade script
 */
function wp_settings() {
	if ( !class_exists( 'wp_settings_api' ) ) {
		include( trailingslashit( plugin_dir_path( __FILE__ ) ) . 'classes/extendd-settings.php' );
	}
	add_filter( 'wp_add_settings_sections', 	array( $this, 'add_settings_section' ) );
	add_filter( 'wp_add_settings_fields',	array( $this, 'add_settings_fields' ) );
			
	$options = get_option( $this->plugin_id, array() );
	if ( isset( $options ) && ( !empty( $options['license_key'] ) && 'valid' === $options['license_active'] ) ) {
		if ( !class_exists( 'EDD_SL_Plugin_Updater' ) ) {
			// load our custom updater
			include( trailingslashit( plugin_dir_path( __FILE__ ) ) . 'classes/EDD_SL_Plugin_Updater.php' );
		}
	
		$edd_updater = new EDD_SL_Plugin_Updater( 'http://frosty.media/', __FILE__,
			array(
				'version'   => $this->version, // current version number
				'license'   => trim( $options['license_key'] ), // license key
				'item_name' => $this->plugin_name, // name of this plugin in the Easy Digital Downloads system
				'author'    => 'Austin Passy' // author of this plugin
			)
		);
	}
}

You may need to adjust the file path, depending on where you have decided to place the file within your plugin’s folder structure.

Step 3 – Add the settings sections

Now that the classes are loaded will set up the settings:

/**
 * Returns new settings section for this plugin
 *
 * @updated 3/6/13
 * @return 	array settings fields
 */
function add_settings_section( $sections ) {
	$sections[] = array(
		'id' 		=> $this->plugin_id,
		'title' 	=> $this->plugin_name, //Must match EDD post_title!
		'basename'	=> plugin_basename( __FILE__ ),
		'version'       => $this->version,
	);
	return $sections;
}

/**
 * Returns new settings fields for this plugin
 *
 * @return 	array settings fields
 */
function add_settings_fields( $settings_fields ) {
	$settings_fields[$this->plugin_id] = array(
		array(
			'name' 			=> 'license_key',
			'label' 		=> __( 'License Key', 'extendd' ),
			'desc' 			=> sprintf( __( 'Enter your license for %s to receive automatic updates', '' ), $this->plugin_name ),
			'type' 			=> 'text',
			'default' 		=> '',
			'placeholder'	        => __( 'Enter your license key', 'extendd' )
		),
		array(
			'name' 			=> 'license_active',
			'label' 		=> '',
			'desc' 			=> '',
			'type' 			=> 'hidden',
			'default' 		=> ''
		),
		array(
			'name' 			=> 'license_deactivate',
			'label' 		=> __( 'De-activate License?', 'extendd' ),
			'desc' 			=> '',
			'type' 			=> 'checkbox',
			'default' 		=> ''
		),
	);	
	return $settings_fields;
}

Everything regarding settings and remote calls is automatically handled by the wp_settings_api class.

There are several parameters we pass to the EDD_SL_Plugin_Updater class:

• $api_url – Always needs to be pointed to Extendd when hosting plugin here.
• $plugin_file – this is the main plugin file. I suggest you use the __FILE__ magic constant provided by PHP. Note, to do this, you must have this snippet placed in your main plugin file.
• $api_args – this is an array of options to pass to the updater:
  • version – this is the current version of the plugin that is installed. It is not the latest available version.
  • license – this is the license key retrieved from the database.
  • item_name – this is the name of our product on Extendd.com
  • author – this is the name of the person or company that wrote the plugin (you!)

That’s it! Your plugin should now have a completely functional automatic upgrade system.

The complete code for the updater might look something like this:

class my_custom_plugin_class {
	
	var $version;

	private $plugin_id,
		$plugin_name;
		
	function __construct() {
		$this->version		= '1.1.6';
		$this->plugin_name	= 'Custom Login Pro';
		$this->plugin_id	= 'wp_custom_login_pro';
		
		/* Extendd */
		$this->wp_settings();
	}
	
	/**
	 * Upgrade script
	 *
	 * @since	11/30/2012
	 */
	function wp_settings() {
		if ( !class_exists( 'wp_settings_api' ) ) {
			include( trailingslashit( plugin_dir_path( __FILE__ ) ) . 'classes/extendd-settings.php' );
		}
		add_filter( 'wp_add_settings_sections', 	array( $this, 'add_settings_section' ) );
		add_filter( 'wp_add_settings_fields',		array( $this, 'add_settings_fields' ) );
				
		$options = get_option( $this->plugin_id, array() );
		if ( isset( $options ) && ( !empty( $options['license_key'] ) && 'valid' === $options['license_active'] ) ) {
			if ( !class_exists( 'EDD_SL_Plugin_Updater' ) ) {
				// load our custom updater
				include( trailingslashit( plugin_dir_path( __FILE__ ) ) . 'classes/EDD_SL_Plugin_Updater.php' );
			}
		
			$edd_updater = new EDD_SL_Plugin_Updater( 'http://frosty.media/', __FILE__,
				array(
					'version'   => $this->version, // current version number
					'license'   => trim( $options['license_key'] ), // license key
					'item_name' => $this->plugin_name, // name of this download on Extendd
					'author'    => 'Austin Passy' // author of this plugin
				)
			);
		}
	}
	
	/**
	 * Returns new settings section for this plugin
	 *
	 * @updated 3/6/13
	 * @return 	array settings fields
	 */
	function add_settings_section( $sections ) {
		$sections[] = array(
			'id' 		=> $this->plugin_id,
			'title' 	=> $this->plugin_name, //Must match download post_title!
			'basename'	=> plugin_basename( __FILE__ ),
			'version'       => $this->version,
		);
		return $sections;
	}
	
	/**
	 * Returns new settings fields for this plugin
	 *
	 * @return 	array settings fields
	 */
	function add_settings_fields( $settings_fields ) {
		$settings_fields[$this->plugin_id] = array(
			array(
				'name' 			=> 'license_key',
				'label' 		=> __( 'License Key', '' ),
				'desc' 			=> sprintf( __( 'Enter your license for %s to receive automatic updates', '' ), $this->plugin_name ),
				'type' 			=> 'text',
				'default' 		=> '',
				'placeholder'	        => __( 'Enter your license key', '' )
			),
			array(
				'name' 			=> 'license_active',
				'label' 		=> '',
				'desc' 			=> '',
				'type' 			=> 'hidden',
				'default' 		=> ''
			),
			array(
				'name' 			=> 'license_deactivate',
				'label' 		=> __( 'De-activate License?', 'extendd' ),
				'desc' 			=> '',
				'type' 			=> 'checkbox',
				'default' 		=> ''
			),
		);	
		return $settings_fields;
	}
}