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    <h3>Editing: wc-product-functions.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * WooCommerce Product Functions
 *
 * Functions for product specific things.
 *
 * @package WooCommerce\Functions
 * @version 3.0.0
 */

use Automattic\Jetpack\Constants;
use Automattic\WooCommerce\Proxies\LegacyProxy;
use Automattic\WooCommerce\Utilities\ArrayUtil;
use Automattic\WooCommerce\Utilities\NumberUtil;
use Automattic\WooCommerce\Internal\ProductImage\MatchImageBySKU;

defined( 'ABSPATH' ) || exit;

/**
 * Standard way of retrieving products based on certain parameters.
 *
 * This function should be used for product retrieval so that we have a data agnostic
 * way to get a list of products.
 *
 * Args and usage: https://github.com/woocommerce/woocommerce/wiki/wc_get_products-and-WC_Product_Query
 *
 * @since  3.0.0
 * @param  array $args Array of args (above).
 * @return array|stdClass Number of pages and an array of product objects if
 *                             paginate is true, or just an array of values.
 */
function wc_get_products( $args ) {
	// Handle some BW compatibility arg names where wp_query args differ in naming.
	$map_legacy = array(
		'numberposts'    =&gt; 'limit',
		'post_status'    =&gt; 'status',
		'post_parent'    =&gt; 'parent',
		'posts_per_page' =&gt; 'limit',
		'paged'          =&gt; 'page',
	);

	foreach ( $map_legacy as $from =&gt; $to ) {
		if ( isset( $args[ $from ] ) ) {
			$args[ $to ] = $args[ $from ];
		}
	}

	$query = new WC_Product_Query( $args );
	return $query-&gt;get_products();
}

/**
 * Main function for returning products, uses the WC_Product_Factory class.
 *
 * This function should only be called after 'init' action is finished, as there might be taxonomies that are getting
 * registered during the init action.
 *
 * @since 2.2.0
 *
 * @param mixed $the_product Post object or post ID of the product.
 * @param array $deprecated Previously used to pass arguments to the factory, e.g. to force a type.
 * @return WC_Product|null|false
 */
function wc_get_product( $the_product = false, $deprecated = array() ) {
	if ( ! did_action( 'woocommerce_init' ) || ! did_action( 'woocommerce_after_register_taxonomy' ) || ! did_action( 'woocommerce_after_register_post_type' ) ) {
		/* translators: 1: wc_get_product 2: woocommerce_init 3: woocommerce_after_register_taxonomy 4: woocommerce_after_register_post_type */
		wc_doing_it_wrong( __FUNCTION__, sprintf( __( '%1$s should not be called before the %2$s, %3$s and %4$s actions have finished.', 'woocommerce' ), 'wc_get_product', 'woocommerce_init', 'woocommerce_after_register_taxonomy', 'woocommerce_after_register_post_type' ), '3.9' );
		return false;
	}
	if ( ! empty( $deprecated ) ) {
		wc_deprecated_argument( 'args', '3.0', 'Passing args to wc_get_product is deprecated. If you need to force a type, construct the product class directly.' );
	}
	return WC()-&gt;product_factory-&gt;get_product( $the_product, $deprecated );
}

/**
 * Get a product object.
 *
 * @see WC_Product_Factory::get_product_classname
 * @since 3.9.0
 * @param string $product_type Product type. If used an invalid type a WC_Product_Simple instance will be returned.
 * @param int    $product_id   Product ID.
 * @return WC_Product
 */
function wc_get_product_object( $product_type, $product_id = 0 ) {
	$classname = WC_Product_Factory::get_product_classname( $product_id, $product_type );

	return new $classname( $product_id );
}

/**
 * Returns whether or not SKUS are enabled.
 *
 * @return bool
 */
function wc_product_sku_enabled() {
	return apply_filters( 'wc_product_sku_enabled', true );
}

/**
 * Returns whether or not product weights are enabled.
 *
 * @return bool
 */
function wc_product_weight_enabled() {
	return apply_filters( 'wc_product_weight_enabled', true );
}

/**
 * Returns whether or not product dimensions (HxWxD) are enabled.
 *
 * @return bool
 */
function wc_product_dimensions_enabled() {
	return apply_filters( 'wc_product_dimensions_enabled', true );
}

/**
 * Clear transient cache for product data.
 *
 * @param int $post_id (default: 0) The product ID.
 */
function wc_delete_product_transients( $post_id = 0 ) {
	// Transient data to clear with a fixed name which may be stale after product updates.
	$transients_to_clear = array(
		'wc_products_onsale',
		'wc_featured_products',
		'wc_outofstock_count',
		'wc_low_stock_count',
	);

	foreach ( $transients_to_clear as $transient ) {
		delete_transient( $transient );
	}

	if ( $post_id &gt; 0 ) {
		// Transient names that include an ID - since they are dynamic they cannot be cleaned in bulk without the ID.
		$post_transient_names = array(
			'wc_product_children_',
			'wc_var_prices_',
			'wc_related_',
			'wc_child_has_weight_',
			'wc_child_has_dimensions_',
		);

		foreach ( $post_transient_names as $transient ) {
			delete_transient( $transient . $post_id );
		}
	}

	// Increments the transient version to invalidate cache.
	WC_Cache_Helper::get_transient_version( 'product', true );

	do_action( 'woocommerce_delete_product_transients', $post_id );
}

/**
 * Function that returns an array containing the IDs of the products that are on sale.
 *
 * @since 2.0
 * @return array
 */
function wc_get_product_ids_on_sale() {
	// Load from cache.
	$product_ids_on_sale = get_transient( 'wc_products_onsale' );

	// Valid cache found.
	if ( false !== $product_ids_on_sale ) {
		return $product_ids_on_sale;
	}

	$data_store          = WC_Data_Store::load( 'product' );
	$on_sale_products    = $data_store-&gt;get_on_sale_products();
	$product_ids_on_sale = wp_parse_id_list( array_merge( wp_list_pluck( $on_sale_products, 'id' ), array_diff( wp_list_pluck( $on_sale_products, 'parent_id' ), array( 0 ) ) ) );

	set_transient( 'wc_products_onsale', $product_ids_on_sale, DAY_IN_SECONDS * 30 );

	return $product_ids_on_sale;
}

/**
 * Function that returns an array containing the IDs of the featured products.
 *
 * @since 2.1
 * @return array
 */
function wc_get_featured_product_ids() {
	// Load from cache.
	$featured_product_ids = get_transient( 'wc_featured_products' );

	// Valid cache found.
	if ( false !== $featured_product_ids ) {
		return $featured_product_ids;
	}

	$data_store           = WC_Data_Store::load( 'product' );
	$featured             = $data_store-&gt;get_featured_product_ids();
	$product_ids          = array_keys( $featured );
	$parent_ids           = array_values( array_filter( $featured ) );
	$featured_product_ids = array_unique( array_merge( $product_ids, $parent_ids ) );

	set_transient( 'wc_featured_products', $featured_product_ids, DAY_IN_SECONDS * 30 );

	return $featured_product_ids;
}

/**
 * Filter to allow product_cat in the permalinks for products.
 *
 * @param  string  $permalink The existing permalink URL.
 * @param  WP_Post $post WP_Post object.
 * @return string
 */
function wc_product_post_type_link( $permalink, $post ) {
	// Abort if post is not a product.
	if ( 'product' !== $post-&gt;post_type ) {
		return $permalink;
	}

	// Abort early if the placeholder rewrite tag isn't in the generated URL.
	if ( false === strpos( $permalink, '%' ) ) {
		return $permalink;
	}

	// Get the custom taxonomy terms in use by this post.
	$terms = get_the_terms( $post-&gt;ID, 'product_cat' );

	if ( ! empty( $terms ) ) {
		$terms           = wp_list_sort(
			$terms,
			array(
				'parent'  =&gt; 'DESC',
				'term_id' =&gt; 'ASC',
			)
		);
		$category_object = apply_filters( 'wc_product_post_type_link_product_cat', $terms[0], $terms, $post );
		$product_cat     = $category_object-&gt;slug;

		if ( $category_object-&gt;parent ) {
			$ancestors = get_ancestors( $category_object-&gt;term_id, 'product_cat' );
			foreach ( $ancestors as $ancestor ) {
				$ancestor_object = get_term( $ancestor, 'product_cat' );
				if ( apply_filters( 'woocommerce_product_post_type_link_parent_category_only', false ) ) {
					$product_cat = $ancestor_object-&gt;slug;
				} else {
					$product_cat = $ancestor_object-&gt;slug . '/' . $product_cat;
				}
			}
		}
	} else {
		// If no terms are assigned to this post, use a string instead (can't leave the placeholder there).
		$product_cat = _x( 'uncategorized', 'slug', 'woocommerce' );
	}

	$find = array(
		'%year%',
		'%monthnum%',
		'%day%',
		'%hour%',
		'%minute%',
		'%second%',
		'%post_id%',
		'%category%',
		'%product_cat%',
	);

	$replace = array(
		date_i18n( 'Y', strtotime( $post-&gt;post_date ) ),
		date_i18n( 'm', strtotime( $post-&gt;post_date ) ),
		date_i18n( 'd', strtotime( $post-&gt;post_date ) ),
		date_i18n( 'H', strtotime( $post-&gt;post_date ) ),
		date_i18n( 'i', strtotime( $post-&gt;post_date ) ),
		date_i18n( 's', strtotime( $post-&gt;post_date ) ),
		$post-&gt;ID,
		$product_cat,
		$product_cat,
	);

	$permalink = str_replace( $find, $replace, $permalink );

	return $permalink;
}
add_filter( 'post_type_link', 'wc_product_post_type_link', 10, 2 );

/**
 * Get the placeholder image URL either from media, or use the fallback image.
 *
 * @param string $size Thumbnail size to use.
 * @return string
 */
function wc_placeholder_img_src( $size = 'woocommerce_thumbnail' ) {
	$src               = WC()-&gt;plugin_url() . '/assets/images/placeholder.png';
	$placeholder_image = get_option( 'woocommerce_placeholder_image', 0 );

	if ( ! empty( $placeholder_image ) ) {
		if ( is_numeric( $placeholder_image ) ) {
			$image = wp_get_attachment_image_src( $placeholder_image, $size );

			if ( ! empty( $image[0] ) ) {
				$src = $image[0];
			}
		} else {
			$src = $placeholder_image;
		}
	}

	return apply_filters( 'woocommerce_placeholder_img_src', $src );
}

/**
 * Get the placeholder image.
 *
 * Uses wp_get_attachment_image if using an attachment ID @since 3.6.0 to handle responsiveness.
 *
 * @param string       $size Image size.
 * @param string|array $attr Optional. Attributes for the image markup. Default empty.
 * @return string
 */
function wc_placeholder_img( $size = 'woocommerce_thumbnail', $attr = '' ) {
	$dimensions        = wc_get_image_size( $size );
	$placeholder_image = get_option( 'woocommerce_placeholder_image', 0 );

	$default_attr = array(
		'class' =&gt; 'woocommerce-placeholder wp-post-image',
		'alt'   =&gt; __( 'Placeholder', 'woocommerce' ),
	);

	$attr = wp_parse_args( $attr, $default_attr );

	if ( wp_attachment_is_image( $placeholder_image ) ) {
		$image_html = wp_get_attachment_image(
			$placeholder_image,
			$size,
			false,
			$attr
		);
	} else {
		$image      = wc_placeholder_img_src( $size );
		$hwstring   = image_hwstring( $dimensions['width'], $dimensions['height'] );
		$attributes = array();

		foreach ( $attr as $name =&gt; $value ) {
			$attributes[] = esc_attr( $name ) . '=&quot;' . esc_attr( $value ) . '&quot;';
		}

		$image_html = '&lt;img src=&quot;' . esc_url( $image ) . '&quot; ' . $hwstring . implode( ' ', $attributes ) . '/&gt;';
	}

	return apply_filters( 'woocommerce_placeholder_img', $image_html, $size, $dimensions );
}

/**
 * Variation Formatting.
 *
 * Gets a formatted version of variation data or item meta.
 *
 * @param array|WC_Product_Variation $variation Variation object.
 * @param bool                       $flat Should this be a flat list or HTML list? (default: false).
 * @param bool                       $include_names include attribute names/labels in the list.
 * @param bool                       $skip_attributes_in_name Do not list attributes already part of the variation name.
 * @return string
 */
function wc_get_formatted_variation( $variation, $flat = false, $include_names = true, $skip_attributes_in_name = false ) {
	$return = '';

	if ( is_a( $variation, 'WC_Product_Variation' ) ) {
		$variation_attributes = $variation-&gt;get_attributes();
		$product              = $variation;
		$variation_name       = $variation-&gt;get_name();
	} else {
		$product        = false;
		$variation_name = '';
		// Remove attribute_ prefix from names.
		$variation_attributes = array();
		if ( is_array( $variation ) ) {
			foreach ( $variation as $key =&gt; $value ) {
				$variation_attributes[ str_replace( 'attribute_', '', $key ) ] = $value;
			}
		}
	}

	$list_type = $include_names ? 'dl' : 'ul';

	if ( is_array( $variation_attributes ) ) {

		if ( ! $flat ) {
			$return = '&lt;' . $list_type . ' class=&quot;variation&quot;&gt;';
		}

		$variation_list = array();

		foreach ( $variation_attributes as $name =&gt; $value ) {
			// If this is a term slug, get the term's nice name.
			if ( taxonomy_exists( $name ) ) {
				$term = get_term_by( 'slug', $value, $name );
				if ( ! is_wp_error( $term ) &amp;&amp; $term &amp;&amp; null !== $term-&gt;name &amp;&amp; '' !== $term-&gt;name ) {
					$value = $term-&gt;name;
				}
			}

			// Do not list attributes already part of the variation name.
			if ( '' === $value || ( $skip_attributes_in_name &amp;&amp; wc_is_attribute_in_product_name( $value, $variation_name ) ) ) {
				continue;
			}

			if ( $include_names ) {
				if ( $flat ) {
					$variation_list[] = wc_attribute_label( $name, $product ) . ': ' . rawurldecode( $value );
				} else {
					$variation_list[] = '&lt;dt&gt;' . wc_attribute_label( $name, $product ) . ':&lt;/dt&gt;&lt;dd&gt;' . rawurldecode( $value ) . '&lt;/dd&gt;';
				}
			} else {
				if ( $flat ) {
					$variation_list[] = rawurldecode( $value );
				} else {
					$variation_list[] = '&lt;li&gt;' . rawurldecode( $value ) . '&lt;/li&gt;';
				}
			}
		}

		if ( $flat ) {
			$return .= implode( ', ', $variation_list );
		} else {
			$return .= implode( '', $variation_list );
		}

		if ( ! $flat ) {
			$return .= '&lt;/' . $list_type . '&gt;';
		}
	}
	return $return;
}

/**
 * Function which handles the start and end of scheduled sales via cron.
 */
function wc_scheduled_sales() {
	$data_store = WC_Data_Store::load( 'product' );

	// Sales which are due to start.
	$product_ids = $data_store-&gt;get_starting_sales();
	if ( $product_ids ) {
		do_action( 'wc_before_products_starting_sales', $product_ids );
		foreach ( $product_ids as $product_id ) {
			$product = wc_get_product( $product_id );

			if ( $product ) {
				$sale_price = $product-&gt;get_sale_price();

				if ( $sale_price ) {
					$product-&gt;set_price( $sale_price );
					$product-&gt;set_date_on_sale_from( '' );
				} else {
					$product-&gt;set_date_on_sale_to( '' );
					$product-&gt;set_date_on_sale_from( '' );
				}

				$product-&gt;save();
			}
		}
		do_action( 'wc_after_products_starting_sales', $product_ids );

		WC_Cache_Helper::get_transient_version( 'product', true );
		delete_transient( 'wc_products_onsale' );
	}

	// Sales which are due to end.
	$product_ids = $data_store-&gt;get_ending_sales();
	if ( $product_ids ) {
		do_action( 'wc_before_products_ending_sales', $product_ids );
		foreach ( $product_ids as $product_id ) {
			$product = wc_get_product( $product_id );

			if ( $product ) {
				$regular_price = $product-&gt;get_regular_price();
				$product-&gt;set_price( $regular_price );
				$product-&gt;set_sale_price( '' );
				$product-&gt;set_date_on_sale_to( '' );
				$product-&gt;set_date_on_sale_from( '' );
				$product-&gt;save();
			}
		}
		do_action( 'wc_after_products_ending_sales', $product_ids );

		WC_Cache_Helper::get_transient_version( 'product', true );
		delete_transient( 'wc_products_onsale' );
	}
}
add_action( 'woocommerce_scheduled_sales', 'wc_scheduled_sales' );

/**
 * Get attachment image attributes.
 *
 * @param array $attr Image attributes.
 * @return array
 */
function wc_get_attachment_image_attributes( $attr ) {
	/*
	 * If the user can manage woocommerce, allow them to
	 * see the image content.
	 */
	if ( current_user_can( 'manage_woocommerce' ) ) {
		return $attr;
	}

	/*
	 * If the user does not have the right capabilities,
	 * filter out the image source and replace with placeholder
	 * image.
	 */
	if ( isset( $attr['src'] ) &amp;&amp; strstr( $attr['src'], 'woocommerce_uploads/' ) ) {
		$attr['src'] = wc_placeholder_img_src();

		if ( isset( $attr['srcset'] ) ) {
			$attr['srcset'] = '';
		}
	}
	return $attr;
}
add_filter( 'wp_get_attachment_image_attributes', 'wc_get_attachment_image_attributes' );


/**
 * Prepare attachment for JavaScript.
 *
 * @param array $response JS version of a attachment post object.
 * @return array
 */
function wc_prepare_attachment_for_js( $response ) {
	/*
	 * If the user can manage woocommerce, allow them to
	 * see the image content.
	 */
	if ( current_user_can( 'manage_woocommerce' ) ) {
		return $response;
	}

	/*
	 * If the user does not have the right capabilities,
	 * filter out the image source and replace with placeholder
	 * image.
	 */
	if ( isset( $response['url'] ) &amp;&amp; strstr( $response['url'], 'woocommerce_uploads/' ) ) {
		$response['full']['url'] = wc_placeholder_img_src();
		if ( isset( $response['sizes'] ) ) {
			foreach ( $response['sizes'] as $size =&gt; $value ) {
				$response['sizes'][ $size ]['url'] = wc_placeholder_img_src();
			}
		}
	}

	return $response;
}
add_filter( 'wp_prepare_attachment_for_js', 'wc_prepare_attachment_for_js' );

/**
 * Track product views.
 */
function wc_track_product_view() {
	if ( ! is_singular( 'product' ) || ! is_active_widget( false, false, 'woocommerce_recently_viewed_products', true ) ) {
		return;
	}

	global $post;

	if ( empty( $_COOKIE['woocommerce_recently_viewed'] ) ) { // @codingStandardsIgnoreLine.
		$viewed_products = array();
	} else {
		$viewed_products = wp_parse_id_list( (array) explode( '|', wp_unslash( $_COOKIE['woocommerce_recently_viewed'] ) ) ); // @codingStandardsIgnoreLine.
	}

	// Unset if already in viewed products list.
	$keys = array_flip( $viewed_products );

	if ( isset( $keys[ $post-&gt;ID ] ) ) {
		unset( $viewed_products[ $keys[ $post-&gt;ID ] ] );
	}

	$viewed_products[] = $post-&gt;ID;

	if ( count( $viewed_products ) &gt; 15 ) {
		array_shift( $viewed_products );
	}

	// Store for session only.
	wc_setcookie( 'woocommerce_recently_viewed', implode( '|', $viewed_products ) );
}

add_action( 'template_redirect', 'wc_track_product_view', 20 );

/**
 * Get product types.
 *
 * @since 2.2
 * @return array
 */
function wc_get_product_types() {
	return (array) apply_filters(
		'product_type_selector',
		array(
			'simple'   =&gt; __( 'Simple product', 'woocommerce' ),
			'grouped'  =&gt; __( 'Grouped product', 'woocommerce' ),
			'external' =&gt; __( 'External/Affiliate product', 'woocommerce' ),
			'variable' =&gt; __( 'Variable product', 'woocommerce' ),
		)
	);
}

/**
 * Check if product sku is unique.
 *
 * @since 2.2
 * @param int    $product_id Product ID.
 * @param string $sku Product SKU.
 * @return bool
 */
function wc_product_has_unique_sku( $product_id, $sku ) {
	/**
	 * Gives plugins an opportunity to verify SKU uniqueness themselves.
	 *
	 * @since 9.0.0
	 *
	 * @param bool|null $has_unique_sku Set to a boolean value to short-circuit the default SKU check.
	 * @param int $product_id The ID of the current product.
	 * @param string $sku The SKU to check for uniqueness.
	 */
	$has_unique_sku = apply_filters( 'wc_product_pre_has_unique_sku', null, $product_id, $sku );
	if ( ! is_null( $has_unique_sku ) ) {
		return boolval( $has_unique_sku );
	}

	$data_store = WC_Data_Store::load( 'product' );
	$sku_found  = $data_store-&gt;is_existing_sku( $product_id, $sku );

	if ( apply_filters( 'wc_product_has_unique_sku', $sku_found, $product_id, $sku ) ) {
		return false;
	}

	return true;
}

/**
 * Check if product unique ID is unique.
 *
 * @since 9.1.0
 * @param int    $product_id Product ID.
 * @param string $global_unique_id Product Unique ID.
 * @return bool
 */
function wc_product_has_global_unique_id( $product_id, $global_unique_id ) {
	/**
	 * Gives plugins an opportunity to verify Unique ID uniqueness themselves.
	 *
	 * @since 9.1.0
	 *
	 * @param bool|null $has_global_unique_id Set to a boolean value to short-circuit the default Unique ID check.
	 * @param int $product_id The ID of the current product.
	 * @param string $sku The Unique ID to check for uniqueness.
	 */
	$has_global_unique_id = apply_filters( 'wc_product_pre_has_global_unique_id', null, $product_id, $global_unique_id );
	if ( ! is_null( $has_global_unique_id ) ) {
		return boolval( $has_global_unique_id );
	}

	$data_store = WC_Data_Store::load( 'product' );
	if ( $data_store-&gt;has_callable( 'is_existing_global_unique_id' ) ) {
		$global_unique_id_found = $data_store-&gt;is_existing_global_unique_id( $product_id, $global_unique_id );
	} else {
		$logger = wc_get_logger();
		$logger-&gt;error( 'The method is_existing_global_unique_id is not implemented in the data store.', array( 'source' =&gt; 'wc_product_has_global_unique_id' ) );
	}
	/**
	 * Gives plugins an opportunity to verify Unique ID uniqueness themselves.
	 *
	 * @since 9.1.0
	 *
	 * @param boolean $global_unique_id_found Whether the Unique ID is found.
	 * @param int $product_id The ID of the current product.
	 * @param string $sku The Unique ID to check for uniqueness.
	 */
	if ( apply_filters( 'wc_product_has_global_unique_id', $global_unique_id_found, $product_id, $global_unique_id ) ) {
		return false;
	}

	return true;
}

/**
 * Force a unique SKU.
 *
 * @since  3.0.0
 * @param  integer $product_id Product ID.
 */
function wc_product_force_unique_sku( $product_id ) {
	$product     = wc_get_product( $product_id );
	$current_sku = $product ? $product-&gt;get_sku( 'edit' ) : '';

	if ( $current_sku ) {
		try {
			$new_sku = wc_product_generate_unique_sku( $product_id, $current_sku );

			if ( $current_sku !== $new_sku ) {
				$product-&gt;set_sku( $new_sku );
				$product-&gt;save();
			}
		} catch ( Exception $e ) {} // @codingStandardsIgnoreLine.
	}
}

/**
 * Recursively appends a suffix until a unique SKU is found.
 *
 * @since  3.0.0
 * @param  integer $product_id Product ID.
 * @param  string  $sku Product SKU.
 * @param  integer $index An optional index that can be added to the product SKU.
 * @return string
 */
function wc_product_generate_unique_sku( $product_id, $sku, $index = 0 ) {
	$generated_sku = 0 &lt; $index ? $sku . '-' . $index : $sku;

	if ( ! wc_product_has_unique_sku( $product_id, $generated_sku ) ) {
		$generated_sku = wc_product_generate_unique_sku( $product_id, $sku, ( $index + 1 ) );
	}

	return $generated_sku;
}

/**
 * Get product ID by SKU.
 *
 * @since  2.3.0
 * @param  string $sku Product SKU.
 * @return int
 */
function wc_get_product_id_by_sku( $sku ) {
	$data_store = WC_Data_Store::load( 'product' );
	return $data_store-&gt;get_product_id_by_sku( $sku );
}

/**
 * Get product ID by Unique ID.
 *
 * @since  9.1.0
 * @param  string $global_unique_id Product Unique ID.
 * @return int|null
 */
function wc_get_product_id_by_global_unique_id( $global_unique_id ) {
	$data_store = WC_Data_Store::load( 'product' );
	if ( $data_store-&gt;has_callable( 'get_product_id_by_global_unique_id' ) ) {
		return $data_store-&gt;get_product_id_by_global_unique_id( $global_unique_id );
	} else {
		$logger = wc_get_logger();
		$logger-&gt;error( 'The method get_product_id_by_global_unique_id is not implemented in the data store.', array( 'source' =&gt; 'wc_get_product_id_by_global_unique_id' ) );
	}
	return null;
}

/**
 * Get attributes/data for an individual variation from the database and maintain it's integrity.
 *
 * @since  2.4.0
 * @param  int $variation_id Variation ID.
 * @return array
 */
function wc_get_product_variation_attributes( $variation_id ) {
	// Build variation data from meta.
	$all_meta                = is_array( get_post_meta( $variation_id ) ) ? get_post_meta( $variation_id ) : array();
	$parent_id               = wp_get_post_parent_id( $variation_id );
	$parent_attributes       = array_filter( (array) get_post_meta( $parent_id, '_product_attributes', true ) );
	$found_parent_attributes = array();
	$variation_attributes    = array();

	// Compare to parent variable product attributes and ensure they match.
	foreach ( $parent_attributes as $attribute_name =&gt; $options ) {
		if ( ! empty( $options['is_variation'] ) ) {
			$attribute                 = 'attribute_' . sanitize_title( $attribute_name );
			$found_parent_attributes[] = $attribute;
			if ( ! array_key_exists( $attribute, $variation_attributes ) ) {
				$variation_attributes[ $attribute ] = ''; // Add it - 'any' will be assumed.
			}
		}
	}

	// Get the variation attributes from meta.
	foreach ( $all_meta as $name =&gt; $value ) {
		// Only look at valid attribute meta, and also compare variation level attributes and remove any which do not exist at parent level.
		if ( 0 !== strpos( $name, 'attribute_' ) || ! in_array( $name, $found_parent_attributes, true ) ) {
			unset( $variation_attributes[ $name ] );
			continue;
		}
		/**
		 * Pre 2.4 handling where 'slugs' were saved instead of the full text attribute.
		 * Attempt to get full version of the text attribute from the parent.
		 */
		if ( sanitize_title( $value[0] ) === $value[0] &amp;&amp; version_compare( get_post_meta( $parent_id, '_product_version', true ), '2.4.0', '&lt;' ) ) {
			foreach ( $parent_attributes as $attribute ) {
				if ( 'attribute_' . sanitize_title( $attribute['name'] ) !== $name ) {
					continue;
				}
				$text_attributes = wc_get_text_attributes( $attribute['value'] );

				foreach ( $text_attributes as $text_attribute ) {
					if ( sanitize_title( $text_attribute ) === $value[0] ) {
						$value[0] = $text_attribute;
						break;
					}
				}
			}
		}

		$variation_attributes[ $name ] = $value[0];
	}

	return $variation_attributes;
}

/**
 * Get all product cats for a product by ID, including hierarchy
 *
 * @since  2.5.0
 * @param  int $product_id Product ID.
 * @return array
 */
function wc_get_product_cat_ids( $product_id ) {
	$product_cats = wc_get_product_term_ids( $product_id, 'product_cat' );

	foreach ( $product_cats as $product_cat ) {
		$product_cats = array_merge( $product_cats, get_ancestors( $product_cat, 'product_cat' ) );
	}

	return $product_cats;
}

/**
 * Gets data about an attachment, such as alt text and captions.
 *
 * @since 2.6.0
 *
 * @param int|null        $attachment_id Attachment ID.
 * @param WC_Product|bool $product WC_Product object.
 *
 * @return array
 */
function wc_get_product_attachment_props( $attachment_id = null, $product = false ) {
	$props      = array(
		'title'   =&gt; '',
		'caption' =&gt; '',
		'url'     =&gt; '',
		'alt'     =&gt; '',
		'src'     =&gt; '',
		'srcset'  =&gt; false,
		'sizes'   =&gt; false,
	);
	$attachment = get_post( $attachment_id );

	if ( $attachment &amp;&amp; 'attachment' === $attachment-&gt;post_type ) {
		$props['title']   = wp_strip_all_tags( $attachment-&gt;post_title );
		$props['caption'] = wp_strip_all_tags( $attachment-&gt;post_excerpt );
		$props['url']     = wp_get_attachment_url( $attachment_id );

		// Alt text.
		$alt_text = array( wp_strip_all_tags( get_post_meta( $attachment_id, '_wp_attachment_image_alt', true ) ), $props['caption'], wp_strip_all_tags( $attachment-&gt;post_title ) );

		if ( $product &amp;&amp; $product instanceof WC_Product ) {
			$alt_text[] = wp_strip_all_tags( get_the_title( $product-&gt;get_id() ) );
		}

		$alt_text     = array_filter( $alt_text );
		$props['alt'] = $alt_text ? reset( $alt_text ) : '';

		// Large version.
		$full_size           = apply_filters( 'woocommerce_gallery_full_size', apply_filters( 'woocommerce_product_thumbnails_large_size', 'full' ) );
		$src                 = wp_get_attachment_image_src( $attachment_id, $full_size );
		$props['full_src']   = $src[0];
		$props['full_src_w'] = $src[1];
		$props['full_src_h'] = $src[2];

		// Gallery thumbnail.
		$gallery_thumbnail                = wc_get_image_size( 'gallery_thumbnail' );
		$gallery_thumbnail_size           = apply_filters( 'woocommerce_gallery_thumbnail_size', array( $gallery_thumbnail['width'], $gallery_thumbnail['height'] ) );
		$src                              = wp_get_attachment_image_src( $attachment_id, $gallery_thumbnail_size );
		$props['gallery_thumbnail_src']   = $src[0];
		$props['gallery_thumbnail_src_w'] = $src[1];
		$props['gallery_thumbnail_src_h'] = $src[2];

		// Thumbnail version.
		$thumbnail_size       = apply_filters( 'woocommerce_thumbnail_size', 'woocommerce_thumbnail' );
		$src                  = wp_get_attachment_image_src( $attachment_id, $thumbnail_size );
		$props['thumb_src']   = $src[0];
		$props['thumb_src_w'] = $src[1];
		$props['thumb_src_h'] = $src[2];

		// Image source.
		$image_size      = apply_filters( 'woocommerce_gallery_image_size', 'woocommerce_single' );
		$src             = wp_get_attachment_image_src( $attachment_id, $image_size );
		$props['src']    = $src[0];
		$props['src_w']  = $src[1];
		$props['src_h']  = $src[2];
		$props['srcset'] = function_exists( 'wp_get_attachment_image_srcset' ) ? wp_get_attachment_image_srcset( $attachment_id, $image_size ) : false;
		$props['sizes']  = function_exists( 'wp_get_attachment_image_sizes' ) ? wp_get_attachment_image_sizes( $attachment_id, $image_size ) : false;
	}
	return $props;
}

/**
 * Get product visibility options.
 *
 * @since 3.0.0
 * @return array
 */
function wc_get_product_visibility_options() {
	return apply_filters(
		'woocommerce_product_visibility_options',
		array(
			'visible' =&gt; __( 'Shop and search results', 'woocommerce' ),
			'catalog' =&gt; __( 'Shop only', 'woocommerce' ),
			'search'  =&gt; __( 'Search results only', 'woocommerce' ),
			'hidden'  =&gt; __( 'Hidden', 'woocommerce' ),
		)
	);
}

/**
 * Get product tax class options.
 *
 * @since 3.0.0
 * @return array
 */
function wc_get_product_tax_class_options() {
	$tax_classes           = WC_Tax::get_tax_classes();
	$tax_class_options     = array();
	$tax_class_options[''] = __( 'Standard', 'woocommerce' );

	if ( ! empty( $tax_classes ) ) {
		foreach ( $tax_classes as $class ) {
			$tax_class_options[ sanitize_title( $class ) ] = $class;
		}
	}
	return $tax_class_options;
}

/**
 * Get stock status options.
 *
 * @since 3.0.0
 * @return array
 */
function wc_get_product_stock_status_options() {
	return apply_filters(
		'woocommerce_product_stock_status_options',
		array(
			'instock'     =&gt; __( 'In stock', 'woocommerce' ),
			'outofstock'  =&gt; __( 'Out of stock', 'woocommerce' ),
			'onbackorder' =&gt; __( 'On backorder', 'woocommerce' ),
		)
	);
}

/**
 * Get backorder options.
 *
 * @since 3.0.0
 * @return array
 */
function wc_get_product_backorder_options() {
	return array(
		'no'     =&gt; __( 'Do not allow', 'woocommerce' ),
		'notify' =&gt; __( 'Allow, but notify customer', 'woocommerce' ),
		'yes'    =&gt; __( 'Allow', 'woocommerce' ),
	);
}

/**
 * Get related products based on product category and tags.
 *
 * @since  3.0.0
 * @param  int   $product_id  Product ID.
 * @param  int   $limit       Limit of results.
 * @param  array $exclude_ids Exclude IDs from the results.
 * @return array
 */
function wc_get_related_products( $product_id, $limit = 5, $exclude_ids = array() ) {

	$product_id     = absint( $product_id );
	$limit          = $limit &gt;= -1 ? $limit : 5;
	$exclude_ids    = array_merge( array( 0, $product_id ), $exclude_ids );
	$transient_name = 'wc_related_' . $product_id;
	$query_args     = http_build_query(
		array(
			'limit'       =&gt; $limit,
			'exclude_ids' =&gt; $exclude_ids,
		)
	);

	$transient     = get_transient( $transient_name );
	$related_posts = $transient &amp;&amp; is_array( $transient ) &amp;&amp; isset( $transient[ $query_args ] ) ? $transient[ $query_args ] : false;

	// We want to query related posts if they are not cached, or we don't have enough.
	if ( false === $related_posts || count( $related_posts ) &lt; $limit ) {

		$cats_array = apply_filters( 'woocommerce_product_related_posts_relate_by_category', true, $product_id ) ? apply_filters( 'woocommerce_get_related_product_cat_terms', wc_get_product_term_ids( $product_id, 'product_cat' ), $product_id ) : array();
		$tags_array = apply_filters( 'woocommerce_product_related_posts_relate_by_tag', true, $product_id ) ? apply_filters( 'woocommerce_get_related_product_tag_terms', wc_get_product_term_ids( $product_id, 'product_tag' ), $product_id ) : array();

		// Don't bother if none are set, unless woocommerce_product_related_posts_force_display is set to true in which case all products are related.
		if ( empty( $cats_array ) &amp;&amp; empty( $tags_array ) &amp;&amp; ! apply_filters( 'woocommerce_product_related_posts_force_display', false, $product_id ) ) {
			$related_posts = array();
		} else {
			$data_store    = WC_Data_Store::load( 'product' );
			$related_posts = $data_store-&gt;get_related_products( $cats_array, $tags_array, $exclude_ids, $limit + 10, $product_id );
		}

		if ( $transient &amp;&amp; is_array( $transient ) ) {
			$transient[ $query_args ] = $related_posts;
		} else {
			$transient = array( $query_args =&gt; $related_posts );
		}

		set_transient( $transient_name, $transient, DAY_IN_SECONDS );
	}

	$related_posts = apply_filters(
		'woocommerce_related_products',
		$related_posts,
		$product_id,
		array(
			'limit'        =&gt; $limit,
			'excluded_ids' =&gt; $exclude_ids,
		)
	);

	if ( apply_filters( 'woocommerce_product_related_posts_shuffle', true ) ) {
		shuffle( $related_posts );
	}

	return array_slice( $related_posts, 0, $limit );
}

/**
 * Retrieves product term ids for a taxonomy.
 *
 * @since  3.0.0
 * @param  int    $product_id Product ID.
 * @param  string $taxonomy   Taxonomy slug.
 * @return array
 */
function wc_get_product_term_ids( $product_id, $taxonomy ) {
	$terms = get_the_terms( $product_id, $taxonomy );
	return ( empty( $terms ) || is_wp_error( $terms ) ) ? array() : wp_list_pluck( $terms, 'term_id' );
}

/**
 * For a given product, and optionally price/qty, work out the price with tax included, based on store settings.
 *
 * @since  3.0.0
 * @param  WC_Product $product WC_Product object.
 * @param  array      $args Optional arguments to pass product quantity and price.
 * @return float|string Price with tax included, or an empty string if price calculation failed.
 */
function wc_get_price_including_tax( $product, $args = array() ) {
	$args = wp_parse_args(
		$args,
		array(
			'qty'   =&gt; '',
			'price' =&gt; '',
		)
	);

	$price = '' !== $args['price'] ? max( 0.0, (float) $args['price'] ) : (float) $product-&gt;get_price();
	$qty   = '' !== $args['qty'] ? max( 0.0, (float) $args['qty'] ) : 1;

	if ( empty( $qty ) ) {
		return 0.0;
	}

	$line_price   = $price * $qty;
	$return_price = $line_price;

	if ( $product-&gt;is_taxable() ) {
		if ( ! wc_prices_include_tax() ) {
			// If the customer is exempt from VAT, set tax total to 0.
			if ( ! empty( WC()-&gt;customer ) &amp;&amp; WC()-&gt;customer-&gt;get_is_vat_exempt() ) {
				$taxes_total = 0.00;
			} else {
				$tax_rates = WC_Tax::get_rates( $product-&gt;get_tax_class() );
				$taxes     = WC_Tax::calc_tax( $line_price, $tax_rates, false );

				if ( 'yes' === get_option( 'woocommerce_tax_round_at_subtotal' ) ) {
					$taxes_total = array_sum( $taxes );
				} else {
					$taxes_total = array_sum( array_map( 'wc_round_tax_total', $taxes ) );
				}
			}

			$return_price = NumberUtil::round( $line_price + $taxes_total, wc_get_price_decimals() );
		} else {
			$tax_rates      = WC_Tax::get_rates( $product-&gt;get_tax_class() );
			$base_tax_rates = WC_Tax::get_base_tax_rates( $product-&gt;get_tax_class( 'unfiltered' ) );

			/**
			 * If the customer is exempt from VAT, remove the taxes here.
			 * Either remove the base or the user taxes depending on woocommerce_adjust_non_base_location_prices setting.
			 */
			if ( ! empty( WC()-&gt;customer ) &amp;&amp; WC()-&gt;customer-&gt;get_is_vat_exempt() ) { // @codingStandardsIgnoreLine.
				$remove_taxes = apply_filters( 'woocommerce_adjust_non_base_location_prices', true ) ? WC_Tax::calc_tax( $line_price, $base_tax_rates, true ) : WC_Tax::calc_tax( $line_price, $tax_rates, true );

				if ( 'yes' === get_option( 'woocommerce_tax_round_at_subtotal' ) ) {
					$remove_taxes_total = array_sum( $remove_taxes );
				} else {
					$remove_taxes_total = array_sum( array_map( 'wc_round_tax_total', $remove_taxes ) );
				}

				$return_price = NumberUtil::round( $line_price - $remove_taxes_total, wc_get_price_decimals() );

				/**
			 * The woocommerce_adjust_non_base_location_prices filter can stop base taxes being taken off when dealing with out of base locations.
			 * e.g. If a product costs 10 including tax, all users will pay 10 regardless of location and taxes.
			 * This feature is experimental @since 2.4.7 and may change in the future. Use at your risk.
			 */
			} elseif ( $tax_rates !== $base_tax_rates &amp;&amp; apply_filters( 'woocommerce_adjust_non_base_location_prices', true ) ) {
				$base_taxes   = WC_Tax::calc_tax( $line_price, $base_tax_rates, true );
				$modded_taxes = WC_Tax::calc_tax( $line_price - array_sum( $base_taxes ), $tax_rates, false );

				if ( 'yes' === get_option( 'woocommerce_tax_round_at_subtotal' ) ) {
					$base_taxes_total   = array_sum( $base_taxes );
					$modded_taxes_total = array_sum( $modded_taxes );
				} else {
					$base_taxes_total   = array_sum( array_map( 'wc_round_tax_total', $base_taxes ) );
					$modded_taxes_total = array_sum( array_map( 'wc_round_tax_total', $modded_taxes ) );
				}

				$return_price = NumberUtil::round( $line_price - $base_taxes_total + $modded_taxes_total, wc_get_price_decimals() );
			}
		}
	}
	return apply_filters( 'woocommerce_get_price_including_tax', $return_price, $qty, $product );
}

/**
 * For a given product, and optionally price/qty, work out the price with tax excluded, based on store settings.
 *
 * @since  3.0.0
 * @param  WC_Product $product WC_Product object.
 * @param  array      $args Optional arguments to pass product quantity and price.
 * @return float|string Price with tax excluded, or an empty string if price calculation failed.
 */
function wc_get_price_excluding_tax( $product, $args = array() ) {
	$args = wp_parse_args(
		$args,
		array(
			'qty'   =&gt; '',
			'price' =&gt; '',
		)
	);

	$price = '' !== $args['price'] ? max( 0.0, (float) $args['price'] ) : (float) $product-&gt;get_price();
	$qty   = '' !== $args['qty'] ? max( 0.0, (float) $args['qty'] ) : 1;

	if ( empty( $qty ) ) {
		return 0.0;
	}

	$line_price = $price * $qty;

	if ( $product-&gt;is_taxable() &amp;&amp; wc_prices_include_tax() ) {
		$order       = ArrayUtil::get_value_or_default( $args, 'order' );
		$customer_id = $order ? $order-&gt;get_customer_id() : 0;
		if ( apply_filters( 'woocommerce_adjust_non_base_location_prices', true ) ) {
			$tax_rates = WC_Tax::get_base_tax_rates( $product-&gt;get_tax_class( 'unfiltered' ) );
		} else {
			$customer  = $customer_id ? wc_get_container()-&gt;get( LegacyProxy::class )-&gt;get_instance_of( WC_Customer::class, $customer_id ) : null;
			$tax_rates = WC_Tax::get_rates( $product-&gt;get_tax_class(), $customer );
		}
		$remove_taxes = WC_Tax::calc_tax( $line_price, $tax_rates, true );
		$return_price = $line_price - array_sum( $remove_taxes ); // Unrounded since we're dealing with tax inclusive prices. Matches logic in cart-totals class. @see adjust_non_base_location_price.
	} else {
		$return_price = $line_price;
	}

	return apply_filters( 'woocommerce_get_price_excluding_tax', $return_price, $qty, $product );
}

/**
 * Returns the price including or excluding tax.
 *
 * By default it's based on the 'woocommerce_tax_display_shop' setting.
 * Set `$arg['display_context']` to 'cart' to base on the 'woocommerce_tax_display_cart' setting instead.
 *
 * @since  3.0.0
 * @since  7.6.0 Added `display_context` argument.
 *
 * @param  WC_Product $product WC_Product object.
 * @param  array      $args Optional arguments to pass product quantity and price.
 * @return float
 */
function wc_get_price_to_display( $product, $args = array() ) {
	$args = wp_parse_args(
		$args,
		array(
			'qty'             =&gt; 1,
			'price'           =&gt; $product-&gt;get_price(),
			'display_context' =&gt; 'shop',
		)
	);

	$price       = $args['price'];
	$qty         = $args['qty'];
	$tax_display = get_option(
		'cart' === $args['display_context'] ? 'woocommerce_tax_display_cart' : 'woocommerce_tax_display_shop'
	);

	return 'incl' === $tax_display ?
		wc_get_price_including_tax(
			$product,
			array(
				'qty'   =&gt; $qty,
				'price' =&gt; $price,
			)
		) :
		wc_get_price_excluding_tax(
			$product,
			array(
				'qty'   =&gt; $qty,
				'price' =&gt; $price,
			)
		);
}

/**
 * Returns the product categories in a list.
 *
 * @param int    $product_id Product ID.
 * @param string $sep (default: ', ').
 * @param string $before (default: '').
 * @param string $after (default: '').
 * @return string
 */
function wc_get_product_category_list( $product_id, $sep = ', ', $before = '', $after = '' ) {
	return get_the_term_list( $product_id, 'product_cat', $before, $sep, $after );
}

/**
 * Returns the product tags in a list.
 *
 * @param int    $product_id Product ID.
 * @param string $sep (default: ', ').
 * @param string $before (default: '').
 * @param string $after (default: '').
 * @return string
 */
function wc_get_product_tag_list( $product_id, $sep = ', ', $before = '', $after = '' ) {
	return get_the_term_list( $product_id, 'product_tag', $before, $sep, $after );
}

/**
 * Callback for array filter to get visible only.
 *
 * @since  3.0.0
 * @param  WC_Product $product WC_Product object.
 * @return bool
 */
function wc_products_array_filter_visible( $product ) {
	return $product &amp;&amp; is_a( $product, 'WC_Product' ) &amp;&amp; $product-&gt;is_visible();
}

/**
 * Callback for array filter to get visible grouped products only.
 *
 * @since  3.1.0
 * @param  WC_Product $product WC_Product object.
 * @return bool
 */
function wc_products_array_filter_visible_grouped( $product ) {
	return $product &amp;&amp; is_a( $product, 'WC_Product' ) &amp;&amp; ( 'publish' === $product-&gt;get_status() || current_user_can( 'edit_product', $product-&gt;get_id() ) );
}

/**
 * Callback for array filter to get products the user can edit only.
 *
 * @since  3.0.0
 * @param  WC_Product $product WC_Product object.
 * @return bool
 */
function wc_products_array_filter_editable( $product ) {
	return $product &amp;&amp; is_a( $product, 'WC_Product' ) &amp;&amp; current_user_can( 'edit_product', $product-&gt;get_id() );
}

/**
 * Callback for array filter to get products the user can view only.
 *
 * @since  3.4.0
 * @param  WC_Product $product WC_Product object.
 * @return bool
 */
function wc_products_array_filter_readable( $product ) {
	return $product &amp;&amp; is_a( $product, 'WC_Product' ) &amp;&amp; current_user_can( 'read_product', $product-&gt;get_id() );
}

/**
 * Sort an array of products by a value.
 *
 * @since  3.0.0
 *
 * @param array  $products List of products to be ordered.
 * @param string $orderby Optional order criteria.
 * @param string $order Ascending or descending order.
 *
 * @return array
 */
function wc_products_array_orderby( $products, $orderby = 'date', $order = 'desc' ) {
	$orderby = strtolower( $orderby );
	$order   = strtolower( $order );
	switch ( $orderby ) {
		case 'title':
		case 'id':
		case 'date':
		case 'modified':
		case 'menu_order':
		case 'price':
			usort( $products, 'wc_products_array_orderby_' . $orderby );
			break;
		case 'none':
			break;
		default:
			shuffle( $products );
			break;
	}
	if ( 'desc' === $order ) {
		$products = array_reverse( $products );
	}
	return $products;
}

/**
 * Sort by title.
 *
 * @since  3.0.0
 * @param  WC_Product $a First WC_Product object.
 * @param  WC_Product $b Second WC_Product object.
 * @return int
 */
function wc_products_array_orderby_title( $a, $b ) {
	return strcasecmp( $a-&gt;get_name(), $b-&gt;get_name() );
}

/**
 * Sort by id.
 *
 * @since  3.0.0
 * @param  WC_Product $a First WC_Product object.
 * @param  WC_Product $b Second WC_Product object.
 * @return int
 */
function wc_products_array_orderby_id( $a, $b ) {
	if ( $a-&gt;get_id() === $b-&gt;get_id() ) {
		return 0;
	}
	return ( $a-&gt;get_id() &lt; $b-&gt;get_id() ) ? -1 : 1;
}

/**
 * Sort by date.
 *
 * @since  3.0.0
 * @param  WC_Product $a First WC_Product object.
 * @param  WC_Product $b Second WC_Product object.
 * @return int
 */
function wc_products_array_orderby_date( $a, $b ) {
	if ( $a-&gt;get_date_created() === $b-&gt;get_date_created() ) {
		return 0;
	}
	return ( $a-&gt;get_date_created() &lt; $b-&gt;get_date_created() ) ? -1 : 1;
}

/**
 * Sort by modified.
 *
 * @since  3.0.0
 * @param  WC_Product $a First WC_Product object.
 * @param  WC_Product $b Second WC_Product object.
 * @return int
 */
function wc_products_array_orderby_modified( $a, $b ) {
	if ( $a-&gt;get_date_modified() === $b-&gt;get_date_modified() ) {
		return 0;
	}
	return ( $a-&gt;get_date_modified() &lt; $b-&gt;get_date_modified() ) ? -1 : 1;
}

/**
 * Sort by menu order.
 *
 * @since  3.0.0
 * @param  WC_Product $a First WC_Product object.
 * @param  WC_Product $b Second WC_Product object.
 * @return int
 */
function wc_products_array_orderby_menu_order( $a, $b ) {
	if ( $a-&gt;get_menu_order() === $b-&gt;get_menu_order() ) {
		return 0;
	}
	return ( $a-&gt;get_menu_order() &lt; $b-&gt;get_menu_order() ) ? -1 : 1;
}

/**
 * Sort by price low to high.
 *
 * @since  3.0.0
 * @param  WC_Product $a First WC_Product object.
 * @param  WC_Product $b Second WC_Product object.
 * @return int
 */
function wc_products_array_orderby_price( $a, $b ) {
	if ( $a-&gt;get_price() === $b-&gt;get_price() ) {
		return 0;
	}
	return ( $a-&gt;get_price() &lt; $b-&gt;get_price() ) ? -1 : 1;
}

/**
 * Queue a product for syncing at the end of the request.
 *
 * @param int $product_id Product ID.
 */
function wc_deferred_product_sync( $product_id ) {
	global $wc_deferred_product_sync;

	if ( empty( $wc_deferred_product_sync ) ) {
		$wc_deferred_product_sync = array();
	}

	$wc_deferred_product_sync[] = $product_id;
}

/**
 * See if the lookup table is being generated already.
 *
 * @since 3.6.0
 * @return bool
 */
function wc_update_product_lookup_tables_is_running() {
	$table_updates_pending = WC()-&gt;queue()-&gt;search(
		array(
			'status'   =&gt; 'pending',
			'group'    =&gt; 'wc_update_product_lookup_tables',
			'per_page' =&gt; 1,
		)
	);

	return (bool) count( $table_updates_pending );
}

/**
 * Populate lookup table data for products.
 *
 * @since 3.6.0
 */
function wc_update_product_lookup_tables() {
	global $wpdb;

	$is_cli = Constants::is_true( 'WP_CLI' );

	if ( ! $is_cli ) {
		WC_Admin_Notices::add_notice( 'regenerating_lookup_table' );
	}

	// Note that the table is not yet generated.
	update_option( 'woocommerce_product_lookup_table_is_generating', true );

	// Make a row per product in lookup table.
	$wpdb-&gt;query(
		&quot;
		INSERT IGNORE INTO {$wpdb-&gt;wc_product_meta_lookup} (`product_id`)
		SELECT
			posts.ID
		FROM {$wpdb-&gt;posts} posts
		WHERE
			posts.post_type IN ('product', 'product_variation')
		&quot;
	);

	// List of column names in the lookup table we need to populate.
	$columns = array(
		'min_max_price',
		'stock_quantity',
		'sku',
		'global_unique_id',
		'stock_status',
		'average_rating',
		'total_sales',
		'downloadable',
		'virtual',
		'onsale',
		'tax_class',
		'tax_status', // When last column is updated, woocommerce_product_lookup_table_is_generating is updated.
	);

	foreach ( $columns as $index =&gt; $column ) {
		if ( $is_cli ) {
			wc_update_product_lookup_tables_column( $column );
		} else {
			WC()-&gt;queue()-&gt;schedule_single(
				time() + $index,
				'wc_update_product_lookup_tables_column',
				array(
					'column' =&gt; $column,
				),
				'wc_update_product_lookup_tables'
			);
		}
	}

	// Rating counts are serialised so they have to be unserialised before populating the lookup table.
	if ( $is_cli ) {
		$rating_count_rows = $wpdb-&gt;get_results(
			&quot;
			SELECT post_id, meta_value FROM {$wpdb-&gt;postmeta}
			WHERE meta_key = '_wc_rating_count'
			AND meta_value != ''
			AND meta_value != 'a:0:{}'
			&quot;,
			ARRAY_A
		);
		wc_update_product_lookup_tables_rating_count( $rating_count_rows );
	} else {
		WC()-&gt;queue()-&gt;schedule_single(
			time() + 10,
			'wc_update_product_lookup_tables_rating_count_batch',
			array(
				'offset' =&gt; 0,
				'limit'  =&gt; 50,
			),
			'wc_update_product_lookup_tables'
		);
	}
}

/**
 * Populate lookup table column data.
 *
 * @since 3.6.0
 * @param string $column Column name to set.
 */
function wc_update_product_lookup_tables_column( $column ) {
	if ( empty( $column ) ) {
		return;
	}
	global $wpdb;
	switch ( $column ) {
		case 'min_max_price':
			$wpdb-&gt;query(
				&quot;
				UPDATE
					{$wpdb-&gt;wc_product_meta_lookup} lookup_table
					INNER JOIN (
						SELECT lookup_table.product_id, MIN( meta_value+0 ) as min_price, MAX( meta_value+0 ) as max_price
						FROM {$wpdb-&gt;wc_product_meta_lookup} lookup_table
						LEFT JOIN {$wpdb-&gt;postmeta} meta1 ON lookup_table.product_id = meta1.post_id AND meta1.meta_key = '_price'
						WHERE
							meta1.meta_value &lt;&gt; ''
						GROUP BY lookup_table.product_id
					) as source on source.product_id = lookup_table.product_id
				SET
					lookup_table.min_price = source.min_price,
					lookup_table.max_price = source.max_price
				&quot;
			);
			break;
		case 'stock_quantity':
			$wpdb-&gt;query(
				&quot;
				UPDATE
					{$wpdb-&gt;wc_product_meta_lookup} lookup_table
					LEFT JOIN {$wpdb-&gt;postmeta} meta1 ON lookup_table.product_id = meta1.post_id AND meta1.meta_key = '_manage_stock'
					LEFT JOIN {$wpdb-&gt;postmeta} meta2 ON lookup_table.product_id = meta2.post_id AND meta2.meta_key = '_stock'
				SET
					lookup_table.stock_quantity = meta2.meta_value
				WHERE
					meta1.meta_value = 'yes'
				&quot;
			);
			break;
		case 'sku':
		case 'global_unique_id':
		case 'stock_status':
		case 'average_rating':
		case 'total_sales':
		case 'tax_class':
		case 'tax_status':
			if ( 'total_sales' === $column ) {
				$meta_key = 'total_sales';
			} elseif ( 'average_rating' === $column ) {
				$meta_key = '_wc_average_rating';
			} else {
				$meta_key = '_' . $column;
			}
			$column = esc_sql( $column );
			// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			$wpdb-&gt;query(
				$wpdb-&gt;prepare(
					&quot;
					UPDATE
						{$wpdb-&gt;wc_product_meta_lookup} lookup_table
						LEFT JOIN {$wpdb-&gt;postmeta} meta ON lookup_table.product_id = meta.post_id AND meta.meta_key = %s
					SET
						lookup_table.`{$column}` = meta.meta_value
					&quot;,
					$meta_key
				)
			);
			// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			break;
		case 'downloadable':
		case 'virtual':
			$column   = esc_sql( $column );
			$meta_key = '_' . $column;
			// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			$wpdb-&gt;query(
				$wpdb-&gt;prepare(
					&quot;
					UPDATE
						{$wpdb-&gt;wc_product_meta_lookup} lookup_table
						LEFT JOIN {$wpdb-&gt;postmeta} meta1 ON lookup_table.product_id = meta1.post_id AND meta1.meta_key = %s
					SET
						lookup_table.`{$column}` = IF ( meta1.meta_value = 'yes', 1, 0 )
					&quot;,
					$meta_key
				)
			);
			// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			break;
		case 'onsale':
			$column   = esc_sql( $column );
			$decimals = absint( wc_get_price_decimals() );

			// phpcs:disable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			$wpdb-&gt;query(
				$wpdb-&gt;prepare(
					&quot;
					UPDATE
						{$wpdb-&gt;wc_product_meta_lookup} lookup_table
						LEFT JOIN {$wpdb-&gt;postmeta} meta1 ON lookup_table.product_id = meta1.post_id AND meta1.meta_key = '_price'
						LEFT JOIN {$wpdb-&gt;postmeta} meta2 ON lookup_table.product_id = meta2.post_id AND meta2.meta_key = '_sale_price'
	  					LEFT JOIN {$wpdb-&gt;postmeta} meta3 ON lookup_table.product_id = meta3.post_id AND meta3.meta_key = '_regular_price'
					SET
						lookup_table.`{$column}` = IF (
							CAST( meta1.meta_value AS DECIMAL ) &gt;= 0
							AND CAST( meta2.meta_value AS CHAR ) != ''
							AND CAST( meta1.meta_value AS DECIMAL( 10, %d ) ) = CAST( meta2.meta_value AS DECIMAL( 10, %d ) )
							AND CAST( meta3.meta_value AS DECIMAL( 10, %d ) ) &gt; CAST( meta2.meta_value AS DECIMAL( 10, %d ) )
						, 1, 0 )
					&quot;,
					$decimals,
					$decimals,
					$decimals,
					$decimals
				)
			);
			// phpcs:enable WordPress.DB.PreparedSQL.InterpolatedNotPrepared
			break;
	}

	// Final column - mark complete.
	if ( 'tax_status' === $column ) {
		delete_option( 'woocommerce_product_lookup_table_is_generating' );
	}
}
add_action( 'wc_update_product_lookup_tables_column', 'wc_update_product_lookup_tables_column' );

/**
 * Populate rating count lookup table data for products.
 *
 * @since 3.6.0
 * @param array $rows Rows of rating counts to update in lookup table.
 */
function wc_update_product_lookup_tables_rating_count( $rows ) {
	if ( ! $rows || ! is_array( $rows ) ) {
		return;
	}
	global $wpdb;

	foreach ( $rows as $row ) {
		$count = array_sum( (array) maybe_unserialize( $row['meta_value'] ) );
		$wpdb-&gt;update(
			$wpdb-&gt;wc_product_meta_lookup,
			array(
				'rating_count' =&gt; absint( $count ),
			),
			array(
				'product_id' =&gt; absint( $row['post_id'] ),
			)
		);
	}
}

/**
 * Populate a batch of rating count lookup table data for products.
 *
 * @since 3.6.2
 * @param array $offset Offset to query.
 * @param array $limit  Limit to query.
 */
function wc_update_product_lookup_tables_rating_count_batch( $offset = 0, $limit = 0 ) {
	global $wpdb;

	if ( ! $limit ) {
		return;
	}

	$rating_count_rows = $wpdb-&gt;get_results(
		$wpdb-&gt;prepare(
			&quot;
			SELECT post_id, meta_value FROM {$wpdb-&gt;postmeta}
			WHERE meta_key = '_wc_rating_count'
			AND meta_value != ''
			AND meta_value != 'a:0:{}'
			ORDER BY post_id ASC
			LIMIT %d, %d
			&quot;,
			$offset,
			$limit
		),
		ARRAY_A
	);

	if ( $rating_count_rows ) {
		wc_update_product_lookup_tables_rating_count( $rating_count_rows );
		WC()-&gt;queue()-&gt;schedule_single(
			time() + 1,
			'wc_update_product_lookup_tables_rating_count_batch',
			array(
				'offset' =&gt; $offset + $limit,
				'limit'  =&gt; $limit,
			),
			'wc_update_product_lookup_tables'
		);
	}
}
add_action( 'wc_update_product_lookup_tables_rating_count_batch', 'wc_update_product_lookup_tables_rating_count_batch', 10, 2 );

/**
 * Attach product featured image. Use image filename to match a product sku when product is not provided.
 *
 * @since 8.5.0
 * @param int        $attachment_id Media attachment ID.
 * @param WC_Product $product Optional product object.
 * @param bool       $save_product If true, the changes in the product will be saved before the method returns.
 * @return void
 */
function wc_product_attach_featured_image( $attachment_id, $product = null, $save_product = true ) {
	$attachment_post = get_post( $attachment_id );
	if ( ! $attachment_post ) {
		return;
	}

	if ( null === $product &amp;&amp; wc_get_container()-&gt;get( MatchImageBySKU::class )-&gt;is_enabled() ) {
		// On upload the attachment post title is the uploaded file's filename.
		$file_name = pathinfo( $attachment_post-&gt;post_title, PATHINFO_FILENAME );
		if ( ! $file_name ) {
			return;
		}

		$product_id = wc_get_product_id_by_sku( $file_name );
		$product    = wc_get_product( $product_id );
	}

	if ( ! $product ) {
		return;
	}

	$product-&gt;set_image_id( $attachment_id );
	if ( $save_product ) {
		$product-&gt;save();
	}
	if ( 0 === $attachment_post-&gt;post_parent ) {
		wp_update_post(
			array(
				'ID'          =&gt; $attachment_id,
				'post_parent' =&gt; $product-&gt;get_id(),
			)
		);
	}
}
add_action( 'add_attachment', 'wc_product_attach_featured_image' );
</textarea><br>
    <input type="submit" value="Save">
</form>