Issue #2908575 by bojanz: Crash when there's only one available country + another one

src/Element/Address.php

@@ -74,19 +74,15 @@ class Address extends FormElement {
   }
 
   /**
-   * {@inheritdoc}
+   * Ensures all keys are set on the provided value.
+   *
+   * @param array $value
+   *   The value.
+   *
+   * @return array
+   *   The modified value.
    */
-  public static function valueCallback(&$element, $input, FormStateInterface $form_state) {
-    if (is_array($input)) {
-      $value = $input;
-    }
-    else {
-      if (!is_array($element['#default_value'])) {
-        $element['#default_value'] = [];
-      }
-      $value = $element['#default_value'];
-    }
-    // Initialize default keys.
+  public static function applyDefaults(array $value) {
     $properties = [
       'given_name', 'additional_name', 'family_name', 'organization',
       'address_line1', 'address_line2', 'postal_code', 'sorting_code',
@@ -102,6 +98,24 @@ class Address extends FormElement {
     return $value;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function valueCallback(&$element, $input, FormStateInterface $form_state) {
+    // Ensure both the default value and the input have all keys set.
+    // Preselect the default country to ensure it's present in the value.
+    if (is_array($input)) {
+      $input = self::applyDefaults($input);
+    }
+    $element['#default_value'] = (array) $element['#default_value'];
+    $element['#default_value'] = self::applyDefaults($element['#default_value']);
+    if (empty($element['#default_value']['country_code']) && $element['#required']) {
+      $element['#default_value']['country_code'] = Country::getDefaultCountry($element['#available_countries']);
+    }
+
+    return is_array($input) ? $input : $element['#default_value'];
+  }
+
   /**
    * Processes the address form element.
    *
@@ -124,11 +138,8 @@ class Address extends FormElement {
     }
     $id_prefix = implode('-', $element['#parents']);
     $wrapper_id = Html::getUniqueId($id_prefix . '-ajax-wrapper');
+    // The #value has the new values on #ajax, the #default_value otherwise.
     $value = $element['#value'];
-    if (empty($value['country_code']) && $element['#required']) {
-      // Preselect the default country so that the other elements can be shown.
-      $value['country_code'] = Country::getDefaultCountry($element['#available_countries']);
-    }
 
     $element = [
       '#tree' => TRUE,
@@ -145,7 +156,7 @@ class Address extends FormElement {
       '#type' => 'address_country',
       '#title' => t('Country'),
       '#available_countries' => $element['#available_countries'],
-      '#default_value' => $value['country_code'],
+      '#default_value' => $element['#default_value']['country_code'],
       '#required' => $element['#required'],
       '#limit_validation_errors' => [],
       '#ajax' => [

src/Element/Zone.php

@@ -60,19 +60,15 @@ class Zone extends FormElement {
   }
 
   /**
-   * {@inheritdoc}
+   * Ensures all keys are set on the provided value.
+   *
+   * @param array $value
+   *   The value.
+   *
+   * @return array
+   *   The modified value.
    */
-  public static function valueCallback(&$element, $input, FormStateInterface $form_state) {
-    if (is_array($input)) {
-      $value = $input;
-    }
-    else {
-      if (!is_array($element['#default_value'])) {
-        $element['#default_value'] = [];
-      }
-      $value = $element['#default_value'];
-    }
-    // Initialize default keys.
+  public static function applyDefaults(array $value) {
     foreach (['label', 'territories'] as $property) {
       if (!isset($value[$property])) {
         $value[$property] = NULL;
@@ -82,6 +78,21 @@ class Zone extends FormElement {
     return $value;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function valueCallback(&$element, $input, FormStateInterface $form_state) {
+    // Ensure both the default value and the input have all keys set.
+    // Preselect the default country to ensure it's present in the value.
+    if (is_array($input)) {
+      $input = self::applyDefaults($input);
+    }
+    $element['#default_value'] = (array) $element['#default_value'];
+    $element['#default_value'] = self::applyDefaults($element['#default_value']);
+
+    return is_array($input) ? $input : $element['#default_value'];
+  }
+
   /**
    * Processes the zone form element.
    *

tests/src/FunctionalJavascript/AddressDefaultWidgetTest.php

@@ -213,7 +213,7 @@ class AddressDefaultWidgetTest extends JavascriptTestBase {
     $this->assertNotEmpty($node, 'Created article ' . $edit['title[0][value]']);
 
     // Now remove 'US' from the list of available countries.
-    $countries = ['FR', 'BR', 'JP'];
+    $countries = ['FR'];
     $edit = [];
     $edit['settings[available_countries][]'] = array_map(function ($country) {
       return $country;
@@ -232,6 +232,13 @@ class AddressDefaultWidgetTest extends JavascriptTestBase {
     $this->assertOptionSelected($field_name . '[0][address][administrative_area]', $address['administrative_area']);
     $this->assertSession()->fieldValueEquals($field_name . '[0][address][postal_code]', $address['postal_code']);
     $this->assertOptionSelected($field_name . '[0][address][country_code]', $country_code);
+    // Confirm that it is possible to switch the country to France, and back.
+    $this->getSession()->getPage()->fillField($field_name . '[0][address][country_code]', 'FR');
+    $this->waitForAjaxToFinish();
+    $this->assertSession()->fieldNotExists($field_name . '[0][address][administrative_area]');
+    $this->getSession()->getPage()->fillField($field_name . '[0][address][country_code]', 'US');
+    $this->waitForAjaxToFinish();
+    $this->assertSession()->fieldExists($field_name . '[0][address][administrative_area]');
 
     // Test the widget with only one available country.
     // Since the field is required, the country selector should be hidden.