Variable product sync

includes/class-wc-product-variable.php

@@ -365,7 +365,7 @@ class WC_Product_Variable extends WC_Product {
 		if ( ! $this->get_manage_stock() ) {
 			$this->set_stock_quantity( '' );
 			$this->set_backorders( 'no' );
-			$this->set_stock_status( $this->child_is_in_stock() ? 'instock' : 'outofstock' );
+			$this->data_store->sync_stock_status( $this );
 
 			// If we are stock managing, backorders are allowed, and we don't have stock, force on backorder status.
 		} elseif ( $this->get_stock_quantity() <= get_option( 'woocommerce_notify_no_stock_amount', 0 ) && 'no' !== $this->get_backorders() ) {
@@ -440,6 +440,16 @@ class WC_Product_Variable extends WC_Product {
 		return $this->data_store->child_is_in_stock( $this );
 	}
 
+	/**
+	 * Is a child on backorder?
+	 *
+	 * @since 3.3.0
+	 * @return boolean
+	 */
+	public function child_is_on_backorder() {
+		return $this->data_store->child_is_on_backorder( $this );
+	}
+
 	/**
 	 * Does a child have a weight set?
 	 * @return boolean

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

@@ -316,6 +316,20 @@ class WC_Product_Variable_Data_Store_CPT extends WC_Product_Data_Store_CPT imple
 		return count( $children ) > $oufofstock_children;
 	}
 
+	/**
+	 * Is a child on backorder?
+	 *
+	 * @since 3.3.0
+	 * @param WC_Product $product Product object.
+	 * @return boolean
+	 */
+	public function child_is_on_backorder( $product ) {
+		global $wpdb;
+		$children             = $product->get_children();
+		$onbackorder_children = $children ? $wpdb->get_var( "SELECT COUNT( post_id ) FROM $wpdb->postmeta WHERE meta_key = '_stock_status' AND meta_value = 'onbackorder' AND post_id IN ( " . implode( ',', array_map( 'absint', $children ) ) . ' )' ) : 0;
+		return (bool) $onbackorder_children;
+	}
+
 	/**
 	 * Syncs all variation names if the parent name is changed.
 	 *
@@ -404,7 +418,13 @@ class WC_Product_Variable_Data_Store_CPT extends WC_Product_Data_Store_CPT imple
 	 * @param WC_Product $product Product object.
 	 */
 	public function sync_stock_status( &$product ) {
-		$product->set_stock_status( $product->child_is_in_stock() ? 'instock' : 'outofstock' );
+		$in_stock = $product->child_is_in_stock();
+		if ( $in_stock ) {
+			$on_backorder = $product->child_is_on_backorder();
+			$product->set_stock_status( $on_backorder ? 'onbackorder' : 'instock' );
+		} else {
+			$product->set_stock_status( 'outofstock' );
+		}
 	}
 
 	/**

tests/unit-tests/product/product-variable.php

@@ -71,4 +71,44 @@ class WC_Tests_Product_Variable extends WC_Unit_Test_Case {
 	 	$this->assertEquals( 3, $product->get_stock_quantity() );
 	 	$this->assertEquals( 'instock', $product->get_stock_status() );
 	}
+
+	/**
+	 * Test that variable products have the correct status when syncing with their children.
+	 *
+	 * @since 3.3.0
+	 */
+	public function test_variable_product_stock_status_sync() {
+		$product = new WC_Product_Variable();
+		$product->save();
+
+		$child1 = new WC_Product_Variation();
+		$child1->set_parent_id( $product->get_id() );
+		$child1->save();
+
+		$child2 = new WC_Product_Variation();
+		$child2->set_parent_id( $product->get_id() );
+		$child2->save();
+
+		$product->set_children( array( $child1->get_id(), $child2->get_id() ) );
+
+		// Product should be in stock if a child is in stock.
+		$child1->set_stock_status( 'instock' );
+		$child1->save();
+		$child2->set_stock_status( 'outofstock' );
+		$child2->save();
+		WC_Product_Variable::sync( $product );
+		$this->assertEquals( 'instock', $product->get_stock_status() );
+
+		// Product should be out of stock if all children are out of stock.
+		$child1->set_stock_status( 'outofstock' );
+		$child1->save();
+		WC_Product_Variable::sync( $product );
+		$this->assertEquals( 'outofstock', $product->get_stock_status() );
+
+		// Product should be on backorder if a child is on backorder.
+		$child1->set_stock_status( 'onbackorder' );
+		$child1->save();
+		WC_Product_Variable::sync( $product );
+		$this->assertEquals( 'onbackorder', $product->get_stock_status() );
+	}
 }