ACP2E-3523: Issue with Default Attribute Option Value Behavior for Multiselect

Author: aplapana

app/code/Magento/Catalog/Controller/Adminhtml/Product/Attribute/Save.php

@@ -272,6 +272,8 @@ public function execute()
             if (array_key_exists('reset_is-default_option', $data) && $data['reset_is-default_option']) {
                 unset($data['reset_is-default_option']);
                 $data['default_value'] = null;
+            } else {
+                $data['default_value'] = implode(",", $data['default']);
             }
 
             $model->addData($data);

app/code/Magento/Catalog/view/adminhtml/templates/catalog/product/attribute/js.phtml

@@ -259,7 +259,7 @@ script;
     setRowVisibility('default_value_yesno', defaultValueYesnoVisibility);
     setRowVisibility('is_global', scopeVisibility);
 
-    var elems = document.getElementsByName('default[]');
+    var elems = document.querySelectorAll('input[name^="default["]');
     for (var i = 0; i < elems.length; i++) {
         elems[i].type = optionDefaultInputType;
     }

app/code/Magento/Catalog/view/adminhtml/templates/catalog/product/attribute/options.phtml

@@ -78,7 +78,7 @@ $stores = $block->getStoresSortedBySortOrder();
                 <input data-role="order" type="hidden" name="option[order][<%- data.id %>]"  value="<%- data.sort_order %>" <?php if ($block->getReadOnly() || $block->canManageOptionDefaultOnly()):?> disabled="disabled"<?php endif; ?>/>
             </td>
             <td class="col-default control-table-actions-cell">
-                <input class="input-radio" type="<%- data.intype %>" name="default[]" value="<%- data.id %>" <%- data.checked %><?php if ($block->getReadOnly()):?>disabled="disabled"<?php endif;?>/>
+                <input class="input-radio" type="<%- data.intype %>" name="default[<%- data.id %>]" value="<%- data.id %>" <%- data.checked %><?php if ($block->getReadOnly()):?>disabled="disabled"<?php endif;?>/>
             </td>
             <?php foreach ($stores as $_store):?>
             <td class="col-<%- data.id %>"><input name="option[value][<%- data.id %>][<?= (int) $_store->getId() ?>]" value="<%- data.store<?= /* @noEscape */ (int) $_store->getId() ?> %>" class="input-text<?php if ($_store->getId() == \Magento\Store\Model\Store::DEFAULT_STORE_ID):?> required-option required-unique<?php endif; ?>" type="text" <?php if ($block->getReadOnly() || $block->canManageOptionDefaultOnly()):?> disabled="disabled"<?php endif;?>/></td>

app/code/Magento/Catalog/view/adminhtml/web/js/options.js

@@ -95,7 +95,7 @@ define([
                     }
                 },
                 reset: function () {
-                    jQuery('input[name="default[]"]').prop('checked', false);
+                    jQuery('input[name^="default["]').prop('checked', false);
                     jQuery('input[name="reset_is-default_option"]').val(1);
                 },
 

app/code/Magento/Eav/Model/ResourceModel/Entity/Attribute.php

@@ -400,7 +400,7 @@ protected function _saveOption(AbstractModel $object)
         }
 
         if ($object->getDefaultValue()) {
-            $defaultValue[] = $object->getDefaultValue();
+            $defaultValue = array_unique(array_merge($defaultValue, explode(",", $object->getDefaultValue())));
         }
 
         $this->_saveDefaultValue($object, $defaultValue);