[SOLO-23136] Update region during admin order address edit (Magento i…

…ssue magento#4000)

app/code/Magento/Sales/view/adminhtml/templates/order/address/form.phtml

@@ -1,24 +1,22 @@
 <?php
 /**
- * Copyright © 2013-2017 Magento, Inc. All rights reserved.
+ * Copyright © Magento, Inc. All rights reserved.
  * See COPYING.txt for license details.
  */
-
 // @codingStandardsIgnoreFile
-
 ?>
 <div class="message message-notice">
     <div class="message-inner">
-        <div class="message-content"><?php /* @escapeNotVerified */ echo __('Changing address information will not recalculate shipping, tax or other order amount.') ?></div>
+        <div class="message-content"><?= /* @escapeNotVerified */ __('Changing address information will not recalculate shipping, tax or other order amount.') ?></div>
     </div>
 </div>
 
 <fieldset class="fieldset admin__fieldset-wrapper">
     <legend class="legend admin__legend">
-        <span><?php /* @escapeNotVerified */ echo $block->getHeaderText() ?></span>
+        <span><?= /* @escapeNotVerified */ $block->getHeaderText() ?></span>
     </legend>
     <br>
-    <div class="form-inline">
-        <?php echo $block->getForm()->toHtml() ?>
+    <div class="form-inline" data-mage-init='{"Magento_Sales/order/edit/address/form":{}}'>
+        <?= $block->getForm()->toHtml() ?>
     </div>
 </fieldset>

app/code/Magento/Sales/view/adminhtml/web/order/edit/address/form.js

@@ -0,0 +1,34 @@
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+define([
+    'jquery'
+], function ($) {
+    'use strict';
+
+    /**
+     * Currently Magento App stores both  region_id and region (as text) values.
+     * To prevent missing region (as text) we need to copy it in hidden field.
+     * @param {Array} config
+     * @param {String} element
+     */
+    return function (config, element) {
+        var form = $(element),
+            regionId = form.find('#region_id'),
+
+            /**
+             * Set region callback
+             */
+            setRegion = function () {
+                form.find('#region').val(regionId.filter(':visible').find(':selected').text());
+            };
+
+        if (regionId.is(':visible')) {
+            setRegion();
+        }
+
+        regionId.on('change', setRegion);
+        form.find('#country_id').on('change', setRegion);
+    };
+});