ENGCOM-6500: #14663 Updating Customer through rest/all/V1/customers/:id resets group_id if group_id not passed in payload #25958

Author: VladimirZaets

app/code/Magento/Customer/Model/ResourceModel/CustomerRepository.php

@@ -17,6 +17,7 @@
 use Magento\Customer\Model\Data\CustomerSecureFactory;
 use Magento\Customer\Model\Delegation\Data\NewOperation;
 use Magento\Customer\Model\Delegation\Storage as DelegatedStorage;
+use Magento\Customer\Model\ResourceModel\Customer\Collection;
 use Magento\Framework\Api\DataObjectHelper;
 use Magento\Framework\Api\ExtensibleDataObjectConverter;
 use Magento\Framework\Api\ExtensionAttribute\JoinProcessorInterface;
@@ -31,6 +32,8 @@
 /**
  * Customer repository.
  *
+ * CRUD operations for customer entity
+ *
  * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
  * @SuppressWarnings(PHPMD.TooManyFields)
  */
@@ -187,8 +190,7 @@ public function save(CustomerInterface $customer, $passwordHash = null)
     {
         /** @var NewOperation|null $delegatedNewOperation */
         $delegatedNewOperation = !$customer->getId() ? $this->delegatedStorage->consumeNewOperation() : null;
-        $prevCustomerData = null;
-        $prevCustomerDataArr = null;
+        $prevCustomerData = $prevCustomerDataArr = null;
         if ($customer->getId()) {
             $prevCustomerData = $this->getById($customer->getId());
             $prevCustomerDataArr = $prevCustomerData->__toArray();
@@ -214,6 +216,7 @@ public function save(CustomerInterface $customer, $passwordHash = null)
                 $prevCustomerData ? $prevCustomerData->getStoreId() : $this->storeManager->getStore()->getId()
             );
         }
+        $this->setCustomerGroupId($customerModel, $customerArr, $prevCustomerDataArr);
         // Need to use attribute set or future updates can cause data loss
         if (!$customerModel->getAttributeSetId()) {
             $customerModel->setAttributeSetId(CustomerMetadataInterface::ATTRIBUTE_SET_ID_CUSTOMER);
@@ -452,4 +455,18 @@ private function setValidationFlag($customerArray, $customerModel)
             $customerModel->setData('ignore_validation_flag', true);
         }
     }
+
+    /**
+     * Set customer group id
+     *
+     * @param Customer $customerModel
+     * @param array $customerArr
+     * @param array $prevCustomerDataArr
+     */
+    private function setCustomerGroupId($customerModel, $customerArr, $prevCustomerDataArr)
+    {
+        if (!isset($customerArr['group_id']) && $prevCustomerDataArr && isset($prevCustomerDataArr['group_id'])) {
+            $customerModel->setGroupId($prevCustomerDataArr['group_id']);
+        }
+    }
 }

app/code/Magento/Customer/Test/Unit/Model/ResourceModel/CustomerRepositoryTest.php

@@ -211,6 +211,7 @@ public function testSave()
                 'setFirstFailure',
                 'setLockExpires',
                 'save',
+                'setGroupId'
             ]
         );
 
@@ -245,9 +246,15 @@ public function testSave()
         $this->customer->expects($this->atLeastOnce())
             ->method('getId')
             ->willReturn($customerId);
-        $this->customer->expects($this->atLeastOnce())
+        $this->customer->expects($this->at(4))
             ->method('__toArray')
             ->willReturn([]);
+        $this->customer->expects($this->at(3))
+            ->method('__toArray')
+            ->willReturn(['group_id' => 1]);
+        $customerModel->expects($this->once())
+            ->method('setGroupId')
+            ->with(1);
         $this->customerRegistry->expects($this->atLeastOnce())
             ->method('retrieve')
             ->with($customerId)