Call save_meta_data before wp_update_post for data stores that use it, and refresh meta cache after.

includes/data-stores/abstract-wc-order-data-store-cpt.php

@@ -113,6 +113,7 @@ abstract class Abstract_WC_Order_Data_Store_CPT extends WC_Data_Store_WP impleme
 	 * @param WC_Order $order
 	 */
 	public function update( &$order ) {
+		$order->save_meta_data();
 		$order->set_version( WC_VERSION );
 
 		$changes = $order->get_changes();
@@ -129,9 +130,9 @@ abstract class Abstract_WC_Order_Data_Store_CPT extends WC_Data_Store_WP impleme
 				'post_modified'     => isset( $changes['date_modified'] ) ? gmdate( 'Y-m-d H:i:s', $order->get_date_modified( 'edit' )->getOffsetTimestamp() ) : current_time( 'mysql' ),
 				'post_modified_gmt' => isset( $changes['date_modified'] ) ? gmdate( 'Y-m-d H:i:s', $order->get_date_modified( 'edit' )->getTimestamp() ) : current_time( 'mysql', 1 ),
 			) );
+			$order->read_meta_data( true ); // Refresh internal meta data, in case things were hooked into `save_post` or another WP hook.
 		}
 		$this->update_post_meta( $order );
-		$order->save_meta_data();
 		$order->apply_changes();
 		$this->clear_caches( $order );
 	}

includes/data-stores/class-wc-coupon-data-store-cpt.php

@@ -127,14 +127,16 @@ class WC_Coupon_Data_Store_CPT extends WC_Data_Store_WP implements WC_Coupon_Dat
 	 * @param WC_Coupon
 	 */
 	public function update( &$coupon ) {
+		$coupon->save_meta_data();
 		$post_data = array(
 			'ID'           => $coupon->get_id(),
 			'post_title'   => $coupon->get_code(),
 			'post_excerpt' => $coupon->get_description(),
 		);
 		wp_update_post( $post_data );
+		$coupon->read_meta_data( true ); // Refresh internal meta data, in case things were hooked into `save_post` or another WP hook.
+
 		$this->update_post_meta( $coupon );
-		$coupon->save_meta_data();
 		$coupon->apply_changes();
 		do_action( 'woocommerce_update_coupon', $coupon->get_id() );
 	}

includes/data-stores/class-wc-product-data-store-cpt.php

@@ -162,6 +162,7 @@ class WC_Product_Data_Store_CPT extends WC_Data_Store_WP implements WC_Object_Da
 	 * @param WC_Product
 	 */
 	public function update( &$product ) {
+		$product->save_meta_data();
 		$changes = $product->get_changes();
 
 		// Only update the post when the post data changes.
@@ -189,6 +190,7 @@ class WC_Product_Data_Store_CPT extends WC_Data_Store_WP implements WC_Object_Da
 				$post_data['post_modified_gmt'] = current_time( 'mysql', 1 );
 			}
 			wp_update_post( $post_data );
+			$product->read_meta_data( true ); // Refresh internal meta data, in case things were hooked into `save_post` or another WP hook.
 		}
 
 		$this->update_post_meta( $product );
@@ -198,7 +200,6 @@ class WC_Product_Data_Store_CPT extends WC_Data_Store_WP implements WC_Object_Da
 		$this->update_version_and_type( $product );
 		$this->handle_updated_props( $product );
 
-		$product->save_meta_data();
 		$product->apply_changes();
 
 		$this->clear_caches( $product );

includes/data-stores/class-wc-product-variation-data-store-cpt.php

@@ -136,6 +136,7 @@ class WC_Product_Variation_Data_Store_CPT extends WC_Product_Data_Store_CPT impl
 	 * @param WC_Product
 	 */
 	public function update( &$product ) {
+		$product->save_meta_data();
 		$changes = $product->get_changes();
 		$title   = $this->generate_product_title( $product );
 
@@ -153,6 +154,7 @@ class WC_Product_Variation_Data_Store_CPT extends WC_Product_Data_Store_CPT impl
 				'post_modified'     => isset( $changes['date_modified'] ) ? gmdate( 'Y-m-d H:i:s', $product->get_date_modified( 'edit' )->getOffsetTimestamp() ) : current_time( 'mysql' ),
 				'post_modified_gmt' => isset( $changes['date_modified'] ) ? gmdate( 'Y-m-d H:i:s', $product->get_date_modified( 'edit' )->getTimestamp() ) : current_time( 'mysql', 1 ),
 			) );
+			$product->read_meta_data( true ); // Refresh internal meta data, in case things were hooked into `save_post` or another WP hook.
 		}
 
 		$this->update_post_meta( $product );
@@ -160,7 +162,6 @@ class WC_Product_Variation_Data_Store_CPT extends WC_Product_Data_Store_CPT impl
 		$this->update_attributes( $product );
 		$this->handle_updated_props( $product );
 
-		$product->save_meta_data();
 		$product->apply_changes();
 
 		$this->update_version_and_type( $product );

tests/framework/helpers/class-wc-helper-product.php

@@ -326,4 +326,12 @@ class WC_Helper_Product {
 
 		return wp_insert_comment( $data );
 	}
+
+	/**
+	 * A helper function for hooking into save_post during the test_product_meta_save_post test.
+	 * @since 3.0.1
+	 */
+	public static function save_post_test_update_meta_data_direct( $id ) {
+		update_post_meta( $id, '_test2', 'world' );
+	}
 }

tests/unit-tests/product/data-store.php

@@ -456,4 +456,33 @@ class WC_Tests_Product_Data_Store extends WC_Unit_Test_Case {
 		$loaded_variation = wc_get_product( $variation->get_id() );
 		$this->assertEquals( "Test Product", $loaded_variation->get_name() );
 	}
+
+	/**
+	 * Test to make sure meta can still be set while hooked using save_post.
+	 * https://github.com/woocommerce/woocommerce/issues/13960
+	 * @since 3.0.01
+	 */
+	function test_product_meta_save_post() {
+		$product = new WC_Product;
+		$product->set_name( 'Test Product' );
+		$product->save();
+		update_post_meta( $product->get_id(), '_test2', 'default' ); // this is the value we don't want to get back.
+
+		// This takes place of WC_Meta_Box do_action( 'woocommerce_admin_process_product_object ' ) just adding simple meta.
+		$product->update_meta_data( '_test', 'hello' );
+		$product->set_name( 'Test Product_' );
+
+		add_action( 'save_post', array( 'WC_Helper_Product', 'save_post_test_update_meta_data_direct' ), 11 );
+		$product->save();
+
+		$test  = get_post_meta( $product->get_id(), '_test', true );
+		$test2 = get_post_meta( $product->get_id(), '_test2', true );
+
+		$this->assertEquals( 'hello', $test );
+		$this->assertEquals( 'world', $test2 ); // this would be 'default' without the force meta refresh in WC_Product_Data_Store::update();
+		$this->assertEquals( 'world', $product->get_meta( '_test2' ) );
+		$this->assertEquals( 'Test Product_', $product->get_name() );
+
+		remove_action( 'save_post', array( 'WC_Helper_Product', 'save_post_test_update_meta_data_direct' ) );
+	}
 }