Add hidden "loaded" flag for repeaters

This allows the repeater to retrieve the load value
from the model only on initialisation. Any further
requests to the repeater (ie. AJAX requests) should
use the POST data.

modules/backend/formwidgets/Repeater.php

@@ -77,6 +77,13 @@ class Repeater extends FormWidgetBase
 
     protected $groupDefinitions = [];
 
+    /**
+     * Determines if repeater has been initialised previously
+     *
+     * @var boolean
+     */
+    protected $loaded = false;
+
     /**
      * @inheritDoc
      */
@@ -95,6 +102,11 @@ class Repeater extends FormWidgetBase
             $this->previewMode = true;
         }
 
+        // Check for loaded flag in POST
+        if ((bool) post($this->alias . '_loaded') === true) {
+            $this->loaded = true;
+        }
+
         $fieldName = $this->formField->getName(false);
 
         $this->processGroupMode();
@@ -197,8 +209,17 @@ class Repeater extends FormWidgetBase
      */
     protected function processItems()
     {
+        $currentValue = ($this->loaded === true)
+            ? post($this->formField->getName())
+            : $this->getLoadValue();
+
+        if ($currentValue === null) {
+            $this->indexCount = 0;
+            $this->formWidgets = [];
+            return;
+        }
+
         $groupMap = [];
-        $currentValue = post($this->formField->getName(), $this->getLoadValue());
 
         // Ensure that the minimum number of items are preinitialized
         // ONLY DONE WHEN NOT IN GROUP MODE
@@ -269,7 +290,10 @@ class Repeater extends FormWidgetBase
      */
     protected function getValueFromIndex($index)
     {
-        $value = post($this->formField->fieldName, $this->getLoadValue());
+        $value = ($this->loaded === true)
+            ? post($this->formField->getName())
+            : $this->getLoadValue();
+
         if (!is_array($value)) {
             $value = [];
         }
@@ -291,7 +315,7 @@ class Repeater extends FormWidgetBase
         $this->vars['widget'] = $this->makeItemFormWidget($this->indexCount, $groupCode);
         $this->vars['indexValue'] = $this->indexCount;
 
-        $itemContainer = '@#'.$this->getId('items');
+        $itemContainer = '@#' . $this->getId('items');
 
         // Increase index count after item is created
         ++$this->indexCount;

modules/backend/formwidgets/repeater/partials/_repeater.htm

@@ -34,6 +34,8 @@
                 </a>
             <?php endif ?>
         </div>
+
+        <input type="hidden" name="<?= $this->alias; ?>_loaded" value="1">
     <?php endif ?>
 
     <script type="text/template" data-group-palette-template>