Fix fatal error in subscription payment method switch in legacy checkout (#4222)

* ensure subscription and pre-order are not converted to Stripe order object in legacy experience

* add changelog

* remove whitespace

* use the variables in condition

Author: Mayisha

changelog.txt

@@ -57,6 +57,7 @@
 * Update - Back button on the settings pages.
 * Update - Use individual product tax status instead of storewide tax setup when determining express checkout availability.
 * Fix - Ensure the subscription object is not converted into a Stripe order object.
+* Fix - Ensure the subscription and pre-order objects are not converted into a Stripe order object in legacy experience.
 * Update - Credit and Bank (BECS and ACSS) icons on the Block checkout page.
 * Fix - Fix BLIK visibility based on account and billing countries.
 * Add - Use Stripe Configuration API to manage payment methods enabled/disabled states.

includes/abstracts/abstract-wc-stripe-payment-gateway.php

@@ -1053,16 +1053,26 @@ public function check_source( $prepared_source ) {
 	 * @param stdClass $source Source information.
 	 */
 	public function save_source_to_order( $order, $source ) {
-		// Store source in the order.
-		$order = WC_Stripe_Order::to_instance( $order );
-
 		$customer_id = $source->customer ?? null;
 		$source_id   = $source->source ?? null;
-		if ( $customer_id ) {
-			$order->set_stripe_customer_id( $customer_id );
-		}
-		if ( $source_id ) {
-			$order->set_source_id( $source_id );
+
+		if ( $this->is_subscription( $order ) || $this->has_pre_order( $order->get_id() ) ) {
+			if ( $customer_id ) {
+				$order->update_meta_data( '_stripe_customer_id', $customer_id );
+			}
+
+			if ( $source_id ) {
+				$order->update_meta_data( '_stripe_source_id', $source_id );
+			}
+		} else {
+			$order = WC_Stripe_Order::to_instance( $order );
+
+			if ( $customer_id ) {
+				$order->set_stripe_customer_id( $customer_id );
+			}
+			if ( $source_id ) {
+				$order->set_source_id( $source_id );
+			}
 		}
 
 		if ( is_callable( [ $order, 'save' ] ) ) {

readme.txt

@@ -167,6 +167,7 @@ If you get stuck, you can ask for help in the [Plugin Forum](https://wordpress.o
 * Update - Back button on the settings pages.
 * Update - Use individual product tax status instead of storewide tax setup when determining express checkout availability.
 * Fix - Ensure the subscription object is not converted into a Stripe order object.
+* Fix - Ensure the subscription and pre-order objects are not converted into a Stripe order object in legacy experience.
 * Update - Credit and Bank (BECS and ACSS) icons on the Block checkout page.
 * Fix - Fix BLIK visibility based on account and billing countries.
 * Add - Use Stripe Configuration API to manage payment methods enabled/disabled states.