Remove unrelated elements when changing item type

application/models/Item.php

@@ -169,6 +169,31 @@ public function getItemTypeElements()
         return $indexedElements;
     }
 
+    /**
+     * Get a complete set of Element IDs associated with this Item.
+     *
+     * @uses Mixin_ElementText::getElementsBySetName()
+     * @uses Table_Element::findByItemType()
+     * @return array Element IDs that are associated with the item type of
+     * the item together with Dublin Core element set.
+     */
+    public function getAssociatedElementIds()
+    {
+        $elementIds = array();
+        $dublinCoreElements = $this->getElementsBySetName('Dublin Core');
+        foreach ($dublinCoreElements as $element) {
+            $elementIds[] = $element->id;
+        }
+        if ($this->item_type_id) {
+            $itemTypeElements = $this->ItemTypeElements;
+            foreach ($itemTypeElements as $element) {
+                $elementIds[] = $element->id;
+            }
+        }
+
+        return $elementIds;
+    }
+
     /**
      * Get a property for display.
      *

application/models/Mixin/ElementText.php

@@ -654,6 +654,11 @@ public function saveElementTexts()
 
         $existingTexts = $this->_textsByElementId;
         $elementIdsFromForm = array_keys($this->_elementsOnForm);
+        $associatedElementIds = array();
+        if (method_exists($this->_record, 'getAssociatedElementIds')) {
+            // Element IDs that are associated to current record
+            $associatedElementIds = (array) $this->_record->getAssociatedElementIds();
+        }
 
         foreach ($this->_textsToSave as $textRecord) {
             if ($this->_replaceElementTexts || in_array($textRecord->element_id, $elementIdsFromForm)) {
@@ -671,13 +676,20 @@ public function saveElementTexts()
         }
 
         // Delete all the remaining, un-matched old texts
+        $elementIdsToDelete = array();
         foreach ($existingTexts as $element_id => $texts) {
             if ($this->_replaceElementTexts || in_array($element_id, $elementIdsFromForm)) {
                 foreach ($texts as $text) {
                     $text->delete();
                 }
+            } elseif ($associatedElementIds && !in_array($element_id, $associatedElementIds)) {
+                // if the element is not part of associated elements, delete it
+                $elementIdsToDelete[] = $element_id;
             }
         }
+        if ($elementIdsToDelete) {
+            $this->deleteElementTextsByElementId($elementIdsToDelete);
+        }
 
         // Cause texts to be re-loaded if accessed after save.
         $this->_recordsAreLoaded = false;