Create a Woocommerce product widget with category filter (ok)

https://stackoverflow.com/questions/46561405/create-a-woocommerce-product-widget-with-category-filter

C:\xampp\htdocs\reset\wp-content\plugins\Products by category\products-by-category.php

<?php
/*
Plugin Name: Products by category
Description: This plugin displays a list of products of a certain category on your website.
Author: Petasos Webdesign
Version: 1.0
Author URI: https://www.petasos.be/
*/

if ( ! defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

class Bi_Widget_Product extends WP_Widget
{
	
	function __construct()
	{
		parent::__construct(
				'woocommerce_ndbProducts',
				__( 'Products by category', 'ndb' ),
				array('description' => __( 'This plugin displays a list of products of a certain category on your website.', 'ndb' )) 
				);
	}

	public function widget( $args, $instance ) {

		extract( $args );
		$title = apply_filters( 'widget_title', $instance['title']);
		$ids   = $instance['ids'];
		$arr_id = explode(',',$ids);
    	$query_args = array(
    		'orderby' => 'menu_order ID',
			'order'   => 'ASC',
  			'post_status'    => 'publish',
  			'post_type'      => 'product',
  			'no_found_rows'  => 1,
  			'posts_per_page' => -1, // -1 needed for displaying all posts of the category
  			'tax_query' => array(
     			array(
      				'taxonomy' => 'product_cat', // The taxonomy we want to query
      				'field' => 'slug', // We use the slug to find our terms
      				'terms' => $arr_id // Our comma seperated list of product categories
     			)
  			)
		);

		$r = new WP_Query( $query_args );
		if ( $r->have_posts() ) {

			echo $before_widget;

			if ( $title )
				echo $before_title . $title . $after_title;

			echo '<ul class="product_list_widget">';

			while ( $r->have_posts()) {
				$r->the_post();
				global $product;
				 ?>
					<li>
						<a href="<?php echo esc_url( get_permalink( $product->id ) ); ?>" title="<?php echo esc_attr( $product->get_title() ); ?>">
							<?php echo $product->get_image(); ?>
							<?php echo $product->get_title(); ?>
						</a>
						<?php if ( ! empty( $show_rating ) ) echo $product->get_rating_html(); ?>
						<?php echo $product->get_price_html(); ?>
					</li>
				<?php
			}

			echo '</ul>';

			echo $after_widget;
		}

		wp_reset_postdata();

		echo $content;

	}
	// Widget Backend

	public function form($instance){
		$title = (isset($instance['title'])) ? $instance['title'] : __( 'Products', 'ndb' );
		$ids = $instance['ids'];
		?>
		<p>
			<label for="<?php echo $this->get_field_id('title'); ?>"><?php _e('Title:'); ?></label>
			<input class="widefat" id="<?php echo $this->get_field_id('title'); ?>"  name="<?php echo $this->get_field_name( 'title' ); ?>" type="text" value="<?php echo esc_attr( $title ); ?>" />
		</p>
		<p>
			<label for="<?php echo $this->get_field_id('ids'); ?>"><?php _e('Category:'); ?></label>
			<input class="widefat" id="<?php echo $this->get_field_id('ids'); ?>"  name="<?php echo $this->get_field_name( 'ids' ); ?>" type="text" value="<?php echo esc_attr( $ids ); ?>" />
		</p>
		<?php

	}

	public function update( $new_instance, $old_instance ) {
		$instance = array();
		$instance['title'] = ( ! empty( $new_instance['title'] ) ) ? strip_tags( $new_instance['title'] ) : '';
		$instance['ids'] = ( ! empty( $new_instance['ids'] ) ) ? strip_tags( $new_instance['ids'] ) : '';
		return $instance;
	}


}

add_action( 'widgets_init', function(){
	register_widget( 'Bi_Widget_Product' );
} );