/widgets/products_on_sale.php

<?php
/**
 * Widget which lists products on sale
 *
 * Displays shopping cart widget
 *
 * DISCLAIMER
 *
 * Do not edit or add directly to this file if you wish to upgrade Jigoshop to newer
 * versions in the future. If you wish to customise Jigoshop core for your needs,
 * please use our GitHub repository to publish essential changes for consideration.
 *
 * @package             Jigoshop
 * @category            Widgets
 * @author              Jigowatt
 * @copyright           Copyright Š 2011-2012 Jigowatt Ltd.
 * @license             http://jigoshop.com/license/commercial-edition
 */
 class Jigoshop_Widget_Products_On_Sale extends WP_Widget {

   	/**
	 * Constructor
	 *
	 * Setup the widget with the available options
	 * Add actions to clear the cache whenever a post is saved|deleted or a theme is switched
	 */
    public function __construct() {
		$options = array(
			'classname'	=> 'widget_products_on_sale',
			'description'	=> __( 'Display a list of products currently onsale', 'jigoshop' )
		);

		// Create the widget
		parent::__construct( 'products-onsale', __( 'Jigoshop: Products On-Sale', 'jigoshop' ), $options );

		// Flush cache after every save
		add_action( 'save_post', array( &$this, 'flush_widget_cache' ) );
		add_action( 'deleted_post', array( &$this, 'flush_widget_cache' ) );
		add_action( 'switch_theme', array( &$this, 'flush_widget_cache' ) );
   	}

	/**
	* Widget
	*
 	* Display the widget in the sidebar
 	* Save output to the cache if empty
	*
 	* @param	array	sidebar arguments
 	* @param	array	instance
 	*/
	public function widget( $args, $instance ) {

		// Get the most recent products from the cache
		$cache = wp_cache_get( 'widget_recent_products', 'widget' );

		// If no entry exists use array
		if ( ! is_array($cache) ) {
			$cache = array();
		}

		// If cached get from the cache
		if ( isset($cache[$args['widget_id']]) ) {
			echo $cache[$args['widget_id']];
			return false;
		}

		// Start buffering
		ob_start();
		extract( $args );

		// Set the widget title
		$title = apply_filters(
			'widget_title',
			( $instance['title'] ) ? $instance['title'] : __( 'Special Offers', 'jigoshop' ),
			$instance,
			$this->id_base
		);

		// Set number of products to fetch
		if( ! $number = absint( $instance['number'] ) ) {
			$number = 5;
		}

		// Set up query
		$query_args = array(
			'posts_per_page' => -1,
			'post_type'	     => 'product',
			'post_status'    => 'publish',
			'orderby'        => 'rand',
			'meta_query'     => array(
				array(
					'key'       => 'visibility',
					'value'     => array( 'catalog', 'visible' ),
					'compare'   => 'IN',
				),
			)
		);

		$q = new WP_Query( $query_args );

		// If there are products
		if( $q->have_posts() ) {

			// Print the widget wrapper & title
			echo $before_widget;
			echo $before_title . $title . $after_title;

			// Open the list
			echo '<ul class="product_list_widget">';

			// Print out each product
			for($i = 0; $q->have_posts() && $i < $number;) : $q->the_post();

				// Get new jigoshop_product instance
				$_product = new jigoshop_product( get_the_ID() );

				// Skip if not on sale
				if( ! $_product->is_on_sale() ) continue; else $i++;

				echo '<li>';
					// Print the product image & title with a link to the permalink
					echo '<a href="'.get_permalink().'" title="'.esc_attr( get_the_title() ).'">';

					// Print the product image
					echo ( has_post_thumbnail() )
						? the_post_thumbnail( 'shop_tiny' )
						: jigoshop_get_image_placeholder( 'shop_tiny' );

					echo '<span class="js_widget_product_title">' . get_the_title() . '</span>';
					echo '</a>';

					// Print the price with html wrappers
					echo '<span class="js_widget_product_price">' . $_product->get_price_html() . '</span>';
				echo '</li>';
			endfor;

			echo '</ul>'; // Close the list

			// Print closing widget wrapper
			echo $after_widget;

			// Reset the global $the_post as this query will have stomped on it
			wp_reset_postdata();
		}
		ob_get_flush();
	}

	/**
	 * Update
	 *
	 * Handles the processing of information entered in the wordpress admin
	 * Flushes the cache & removes entry from options array
	 *
	 * @param	array	new instance
	 * @param	array	old instance
	 * @return	array	instance
	 */
	public function update( $new_instance, $old_instance ) {
		$instance = $old_instance;

		// Save the new values
		$instance['title'] = strip_tags( $new_instance['title'] );
		$instance['number'] = absint( $new_instance['number'] );

		// Flush the cache
		$this->flush_widget_cache();

		// Remove the cache entry from the options array
		$alloptions = wp_cache_get( 'alloptions', 'options' );
		if ( isset( $alloptions['widget_recent_products'] ) ) {
			delete_option( 'widget_recent_products' );
		}

		return $instance;
	}

	/**
	 * Flush Widget Cache
	 *
	 * Flushes the cached output
	 */
	public function flush_widget_cache() {
		wp_cache_delete( 'widget_recent_products', 'widget' );
	}

	/**
	 * Form
	 *
	 * Displays the form for the wordpress admin
	 *
	 * @param	array	instance
	 */
	public function form( $instance ) {

		// Get instance data
		$title 		= isset( $instance['title'] ) ? esc_attr( $instance['title'] ) : null;
		$number 	= isset( $instance['number'] ) ? absint( $instance['number'] ) : 5;

		// Widget Title
		echo "
		<p>
			<label for='{$this->get_field_id( 'title' )}'>" . __( 'Title:', 'jigoshop' ) . "</label>
			<input class='widefat' id='{$this->get_field_id( 'title' )}' name='{$this->get_field_name( 'title' )}' type='text' value='{$title}' />
		</p>";

		// Number of posts to fetch
		echo "
		<p>
			<label for='{$this->get_field_id( 'number' )}'>" . __( 'Number of products to show:', 'jigoshop' ) . "</label>
			<input id='{$this->get_field_id( 'number' )}' name='{$this->get_field_name( 'number' )}' type='number' min='1' value='{$number}' />
		</p>";
	}
 }