Added key mode to taglist form widget

Alternative implementation #2958
Fixes #2958

modules/backend/formwidgets/TagList.php

@@ -42,6 +42,11 @@ class TagList extends FormWidgetBase
      */
     public $nameFrom = 'name';
 
+    /**
+     * @var bool Use the key instead of value for saving and reading data.
+     */
+    public $useKey = false;
+
     //
     // Object properties
     //
@@ -62,6 +67,7 @@ class TagList extends FormWidgetBase
             'options',
             'mode',
             'nameFrom',
+            'useKey',
         ]);
     }
 
@@ -71,6 +77,7 @@ class TagList extends FormWidgetBase
     public function render()
     {
         $this->prepareVars();
+
         return $this->makePartial('taglist');
     }
 
@@ -79,6 +86,7 @@ class TagList extends FormWidgetBase
      */
     public function prepareVars()
     {
+        $this->vars['useKey'] = $this->useKey;
         $this->vars['field'] = $this->formField;
         $this->vars['fieldOptions'] = $this->getFieldOptions();
         $this->vars['selectedValues'] = $this->getLoadValue();

modules/backend/formwidgets/taglist/partials/_taglist.htm

@@ -1,6 +1,6 @@
 <?php
     $selectedValues = is_array($selectedValues) ? $selectedValues : [];
-    $availableOptions = array_unique(array_merge($selectedValues, $fieldOptions));
+    $availableOptions = $useKey ? $fieldOptions : array_unique(array_merge($selectedValues, $fieldOptions));
 ?>
 <!-- Tag List -->
 <select
@@ -10,8 +10,12 @@
     <?php if ($customSeparators): ?>data-token-separators="<?= $customSeparators ?>"<?php endif ?>
     multiple
     <?= $field->getAttributes() ?>>
-    <?php foreach ($availableOptions as $option): ?>
+    <?php foreach ($availableOptions as $key => $option): ?>
         <?php if (!strlen($option)) continue ?>
-        <option value="<?= e($option) ?>" <?= in_array($option, $selectedValues) ? 'selected="selected"' : '' ?>><?= e(trans($option)) ?></option>
+        <?php if ($useKey): ?>
+            <option value="<?= e($key) ?>" <?= in_array($key, $selectedValues) ? 'selected="selected"' : '' ?>><?= e(trans($option)) ?></option>
+        <?php else: ?>
+            <option value="<?= e($option) ?>" <?= in_array($option, $selectedValues) ? 'selected="selected"' : '' ?>><?= e(trans($option)) ?></option>
+        <?php endif ?>
     <?php endforeach ?>
 </select>