Move meta handling saving/getting logic to a data store, and fix cache handling for meta to reduce queries.

includes/abstracts/abstract-wc-data.php

@@ -59,6 +59,12 @@ abstract class WC_Data {
 	 */
 	protected $data_store;
 
+	/**
+	 * Contains a reference to the data store for meta handling.
+	 * @var object
+	 */
+	protected $meta_data_store;
+
 	/**
 	 * Stores meta in cache for future reads.
 	 * A group must be set to to enable caching.
@@ -98,7 +104,8 @@ abstract class WC_Data {
 	 * @param int|object|array $read ID to load from the DB (optional) or already queried data.
 	 */
 	public function __construct( $read = 0 ) {
-		$this->default_data = $this->data;
+		$this->default_data    = $this->data;
+		$this->meta_data_store = WC_Data_Store::load( 'meta' );
 	}
 
 	/**
@@ -111,6 +118,26 @@ abstract class WC_Data {
 		return $this->data_store;
 	}
 
+	/**
+	 * Get the meta type for this data type.
+	 *
+	 * @since 2.7.0
+	 * @return string
+	 */
+	public function get_meta_type() {
+		return $this->meta_type;
+	}
+
+	/**
+	 * Get the object ID field this data type.
+	 *
+	 * @since 2.7.0
+	 * @return string
+	 */
+	public function get_object_id_field_for_meta() {
+		return $this->object_id_field_for_meta;
+	}
+
 	/**
 	 * Returns the unique ID for this object.
 	 * @return int
@@ -330,7 +357,7 @@ abstract class WC_Data {
 	 * @param int $mid Meta ID
 	 */
 	public function delete_meta_data_by_mid( $mid ) {
-		$array_keys         = array_keys( wp_list_pluck( $this->meta_data, 'id' ), $mid );
+		$array_keys = array_keys( wp_list_pluck( $this->meta_data, 'id' ), $mid );
 		if ( $array_keys ) {
 			foreach ( $array_keys as $array_key ) {
 				$this->meta_data[ $array_key ]->value = null;
@@ -350,10 +377,12 @@ abstract class WC_Data {
 
 	/**
 	 * Read Meta Data from the database. Ignore any internal properties.
+	 *
 	 * @since 2.6.0
+	 * @param bool $force_read True to force a new DB read (and update cache).
 	 */
-	public function read_meta_data() {
+	public function read_meta_data( $force_read = false ) {
-		$this->meta_data = array();
+		$this->meta_data  = array();
 		$cache_loaded     = false;
 
 		if ( ! $this->get_id() ) {
@@ -361,37 +390,34 @@ abstract class WC_Data {
 		}
 
 		if ( ! empty( $this->cache_group ) ) {
-			$cache_key   = WC_Cache_Helper::get_cache_prefix( $this->cache_group ) . $this->get_id();
+			$cache_key = WC_Cache_Helper::get_cache_prefix( $this->cache_group ) . 'object_meta_' . $this->get_id();
-			$cached_meta = wp_cache_get( $cache_key, $this->cache_group );
+		}
 
-			if ( false !== $cached_meta ) {
+		if ( ! $force_read ) {
-				$this->meta_data = $cached_meta;
+			if ( ! empty( $this->cache_group ) ) {
-				$cache_loaded = true;
+				$cached_meta = wp_cache_get( $cache_key, $this->cache_group );
+				if ( false !== $cached_meta ) {
+					$this->meta_data = $cached_meta;
+					$cache_loaded    = true;
+				}
 			}
 		}
 
 		if ( ! $cache_loaded ) {
-			global $wpdb;
+			$raw_meta_data  = $this->meta_data_store->read_meta( $this );
-			$db_info = $this->get_db_info();
-			$raw_meta_data = $wpdb->get_results( $wpdb->prepare( "
-				SELECT " . $db_info['meta_id_field'] . ", meta_key, meta_value
-				FROM " . $db_info['table'] . "
-				WHERE " . $db_info['object_id_field'] . "=%d AND meta_key NOT LIKE 'wp\_%%' ORDER BY " . $db_info['meta_id_field'] . "
-			", $this->get_id() ) );
-
 			if ( $raw_meta_data ) {
 				$raw_meta_data = array_filter( $raw_meta_data, array( $this, 'exclude_internal_meta_keys' ) );
 				foreach ( $raw_meta_data as $meta ) {
 					$this->meta_data[] = (object) array(
-						'id'    => (int) $meta->{ $db_info['meta_id_field'] },
+						'id'    => (int) $meta->meta_id,
 						'key'   => $meta->meta_key,
 						'value' => maybe_unserialize( $meta->meta_value ),
 					);
 				}
-			}
 
-			if ( ! empty( $this->cache_group ) ) {
+				if ( ! empty( $this->cache_group ) ) {
-				wp_cache_set( $cache_key, $this->meta_data, $this->cache_group );
+					wp_cache_set( $cache_key, $this->meta_data, $this->cache_group );
+				}
 			}
 		}
 	}
@@ -404,55 +430,21 @@ abstract class WC_Data {
 		foreach ( $this->meta_data as $array_key => $meta ) {
 			if ( is_null( $meta->value ) ) {
 				if ( ! empty( $meta->id ) ) {
-					delete_metadata_by_mid( $this->meta_type, $meta->id );
+					$this->meta_data_store->delete_meta( $this, $meta );
 				}
 			} elseif ( empty( $meta->id ) ) {
-				$new_meta_id = add_metadata( $this->meta_type, $this->get_id(), $meta->key, $meta->value, false );
+				$new_meta_id                       = $this->meta_data_store->add_meta( $this, $meta );
 				$this->meta_data[ $array_key ]->id = $new_meta_id;
 			} else {
-				update_metadata_by_mid( $this->meta_type, $meta->id, $meta->value, $meta->key );
+				$this->meta_data_store->update_meta( $this, $meta );
 			}
 		}
 
 		if ( ! empty( $this->cache_group ) ) {
 			WC_Cache_Helper::incr_cache_prefix( $this->cache_group );
 		}
-		$this->read_meta_data();
-	}
 
-	/**
+		$this->read_meta_data( true );
-	 * Table structure is slightly different between meta types, this function will return what we need to know.
-	 * @since 2.6.0
-	 * @return array Array elements: table, object_id_field, meta_id_field
-	 */
-	protected function get_db_info() {
-		global $wpdb;
-
-		$meta_id_field   = 'meta_id'; // for some reason users calls this umeta_id so we need to track this as well.
-		$table           = $wpdb->prefix;
-
-		// If we are dealing with a type of metadata that is not a core type, the table should be prefixed.
-		if ( ! in_array( $this->meta_type, array( 'post', 'user', 'comment', 'term' ) ) ) {
-			$table .= 'woocommerce_';
-		}
-
-		$table .= $this->meta_type . 'meta';
-		$object_id_field = $this->meta_type . '_id';
-
-		// Figure out our field names.
-		if ( 'user' === $this->meta_type ) {
-			$meta_id_field   = 'umeta_id';
-		}
-
-		if ( ! empty( $this->object_id_field_for_meta ) ) {
-			$object_id_field = $this->object_id_field_for_meta;
-		}
-
-		return array(
-			'table'           => $table,
-			'object_id_field' => $object_id_field,
-			'meta_id_field'   => $meta_id_field,
-		);
 	}
 
 	/**

includes/abstracts/abstract-wc-product.php

@@ -27,6 +27,12 @@ class WC_Product extends WC_Abstract_Legacy_Product {
 	 */
 	protected $post_type = 'product';
 
+	/**
+	 * Cache group.
+	 * @var string
+	 */
+	protected $cache_group = 'products';
+
 	/**
 	 * Stores product data.
 	 *

includes/class-wc-coupon.php

@@ -74,6 +74,12 @@ class WC_Coupon extends WC_Legacy_Coupon {
 	 */
 	protected $meta_type = 'post';
 
+	/**
+	 * Cache group.
+	 * @var string
+	 */
+	protected $cache_group = 'coupons';
+
 	/**
 	 * Data stored in meta keys, but not considered "meta" for a coupon.
 	 * @since 2.7.0

includes/data-stores/class-wc-meta-data-store.php

@@ -0,0 +1,99 @@
+<?php
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/**
+ * Meta data store.
+ *
+ * @version  2.7.0
+ * @category Class
+ * @author   WooCommerce
+ */
+class WC_Meta_Data_Store implements WC_Meta_Data_Store_Interface {
+
+	/**
+	 * Returns an array of objects containing meta_id, meta_key, and meta_value.
+	 */
+	public function read_meta( $object ) {
+		global $wpdb;
+		$db_info = $this->get_db_info( $object );
+		return $wpdb->get_results( $wpdb->prepare( "
+			SELECT " . $db_info['meta_id_field'] . " as meta_id, meta_key, meta_value
+			FROM " . $db_info['table'] . "
+			WHERE " . $db_info['object_id_field'] . "=%d AND meta_key NOT LIKE 'wp\_%%' ORDER BY " . $db_info['meta_id_field'] . "
+		", $object->get_id() ) );
+	}
+
+	/**
+	 * Deletes a piece of meta.
+	 *
+	 * @since 2.7.0
+	 * @param WC_Data $object
+	 * @param object $meta Object containing ->id, ->key, and possibily ->value.
+	 */
+	public function delete_meta( $object, $meta ) {
+		delete_metadata_by_mid( $object->get_meta_type(), $meta->id );
+	}
+
+	/**
+	 * Adds meta.
+	 *
+	 * @since 2.7.0
+	 * @param WC_Data $object
+	 * @param object $meta Object containing ->key and ->value
+	 * @return int Meta ID
+	 */
+	public function add_meta( $object, $meta ) {
+		return add_metadata( $object->get_meta_type(), $object->get_id(), $meta->key, $meta->value, false );
+	}
+
+	/**
+	 * Updates meta.
+	 *
+	 * @since 2.7.0
+	 * @param WC_Data $object
+	 * @param object $meta Object containing ->id, ->key and ->value
+	 */
+	public function update_meta( $object, $meta ) {
+		update_metadata_by_mid( $object->get_meta_type(), $meta->id, $meta->value, $meta->key );
+	}
+
+	/**
+	 * Table structure is slightly different between meta types, this function will return what we need to know.
+	 *
+	 * @since  2.7.0
+	 * @param  WC_Data
+	 * @return array Array elements: table, object_id_field, meta_id_field
+	 */
+	protected function get_db_info( &$object ) {
+		global $wpdb;
+
+		$meta_id_field   = 'meta_id'; // for some reason users calls this umeta_id so we need to track this as well.
+		$table           = $wpdb->prefix;
+
+		// If we are dealing with a type of metadata that is not a core type, the table should be prefixed.
+		if ( ! in_array( $object->get_meta_type(), array( 'post', 'user', 'comment', 'term' ) ) ) {
+			$table .= 'woocommerce_';
+		}
+
+		$table          .= $object->get_meta_type() . 'meta';
+		$object_id_field = $object->get_meta_type() . '_id';
+
+		// Figure out our field names.
+		if ( 'user' === $object->get_meta_type() ) {
+			$meta_id_field = 'umeta_id';
+		}
+
+		if ( ! empty( $object->get_object_id_field_for_meta() ) ) {
+			$object_id_field = $object->get_object_id_field_for_meta();
+		}
+
+		return array(
+			'table'           => $table,
+			'object_id_field' => $object_id_field,
+			'meta_id_field'   => $meta_id_field,
+		);
+	}
+
+}

includes/data-stores/interfaces/class-wc-meta-data-store-interface.php

@@ -0,0 +1,17 @@
+<?php
+if ( ! defined( 'ABSPATH' ) ) {
+	exit;
+}
+
+/**
+ * WC Meta Data Store Interface
+ *
+ * Functions that must be defined by meta store classes.
+ *
+ * @version  2.7.0
+ * @category Interface
+ * @author   WooCommerce
+ */
+interface WC_Meta_Data_Store_Interface {
+
+}

tests/unit-tests/coupon/data.php

@@ -57,7 +57,8 @@ class WC_Tests_Coupon_Data extends WC_Unit_Test_Case {
 		$this->expected_doing_it_wrong = array_merge( $this->expected_doing_it_wrong, $legacy_keys );
 
 		$coupon = WC_Helper_Coupon::create_coupon();
-		add_post_meta( $coupon->get_id(), 'test_coupon_field', 'testing', true );
+		$coupon->add_meta_data( 'test_coupon_field', 'testing', true );
+		$coupon->save_meta_data();
 		$coupon = new WC_Coupon( $coupon->get_id() );
 
 		$this->assertEquals( $coupon->get_id(), $coupon->id );
@@ -194,7 +195,9 @@ class WC_Tests_Coupon_Data extends WC_Unit_Test_Case {
 		$coupon     = WC_Helper_Coupon::create_coupon();
 		$coupon_id  = $coupon->get_id();
 		$meta_value = time() . '-custom-value';
-		add_post_meta( $coupon_id, 'test_coupon_field', $meta_value, true );
+		$coupon->add_meta_data( 'test_coupon_field', $meta_value, true );
+		$coupon->save_meta_data();
+
 		$coupon = new WC_Coupon( $coupon_id );
 		$custom_fields = $coupon->get_meta_data();
 		$this->assertCount( 1, $custom_fields );

woocommerce.php

@@ -322,6 +322,7 @@ final class WooCommerce {
 		include_once( WC_ABSPATH . 'includes/data-stores/abstract-wc-order-data-store-cpt.php' );
 		include_once( WC_ABSPATH . 'includes/data-stores/class-wc-order-data-store-cpt.php' );
 		include_once( WC_ABSPATH . 'includes/data-stores/class-wc-order-refund-data-store-cpt.php' );
+		include_once( WC_ABSPATH . 'includes/data-stores/class-wc-meta-data-store.php' );
 
 		$this->query = new WC_Query();
 		$this->api   = new WC_API();