MAGETWO-84000: Undefined index: region_id is presented after save customer address

Author: Oleksandr Iegorov

app/code/Magento/Customer/Block/Address/Edit.php

@@ -139,9 +139,11 @@ protected function _prepareLayout()
 
         if ($postedData = $this->_customerSession->getAddressFormData(true)) {
             $postedData['region'] = [
-                'region_id' => $postedData['region_id'] ?? null,
                 'region' => $postedData['region'] ?? null,
             ];
+            if (!empty($postedData['region_id'])) {
+                $postedData['region']['region_id'] = $postedData['region_id'];
+            }
             $this->dataObjectHelper->populateWithArray(
                 $this->_address,
                 $postedData,

app/code/Magento/Customer/Test/Unit/Block/Address/EditTest.php

@@ -101,15 +101,15 @@ protected function setUp()
         );
     }
 
-    public function testSetLayoutWithOwnAddressAndPostedData()
+    /**
+     * @param array $postedData
+     * @dataProvider postedDataProvider
+     */
+    public function testSetLayoutWithOwnAddressAndPostedData(array $postedData)
     {
         $addressId = 1;
         $customerId = 1;
         $title = __('Edit Address');
-        $postedData = [
-            'region_id' => 1,
-            'region' => 'region',
-        ];
         $newPostedData = $postedData;
         $newPostedData['region'] = $postedData;
 
@@ -169,6 +169,21 @@ public function testSetLayoutWithOwnAddressAndPostedData()
         $this->assertEquals($layoutMock, $this->model->getLayout());
     }
 
+    /**
+     * @return array
+     */
+    public function postedDataProvider()
+    {
+        return [
+            [
+                ['region_id' => 1, 'region' => 'region']
+            ],
+            [
+                ['region' => 'region without id']
+            ]
+        ];
+    }
+
     /**
      * @throws \Magento\Framework\Exception\LocalizedException
      * @SuppressWarnings(PHPMD.ExcessiveMethodLength)