Added upgrade script

code/UpgradeBasicGalleriesTask.php

@@ -0,0 +1,53 @@
+<?php
+
+namespace PurpleSpider\MySite;
+
+use SilverStripe\Dev\BuildTask;
+use SilverStripe\CMS\Model\SiteTree;
+use SilverStripe\ORM\Queries\SQLSelect;
+use SilverStripe\ORM\Queries\SQLUpdate;
+
+
+class UpgradeBasicGalleriesTask extends BuildTask {
+
+    protected $title = 'Upgrade Basic Galleries';
+    private static $segment = 'upgrade-basic-galleries';
+    protected $description = "Applies database updates for Basic Galleries polymorphic update";
+
+    public function run($request) {
+
+        $sqlQuery = new SQLSelect();
+        $sqlQuery->setFrom('PhotoGalleryImage');
+        $sqlQuery->selectField('PhotoGalleryPageID');
+        $result = $sqlQuery->execute();
+
+        $updatecount = 0;
+
+        foreach($result as $row) {
+            if(isset($row['PhotoGalleryPageID']) && $row['PhotoGalleryPageID']) {
+                $page = SiteTree::get()->byID($row['PhotoGalleryPageID']);
+                if($page->exists()) {
+                    $pageClassname = $page->ClassName;
+                    $update = SQLUpdate::create('"PhotoGalleryImage"')->addWhere(['ID' => $row['ID']]);
+                    $update->assign('"AlbumID"', $row['PhotoGalleryPageID']);
+                    $update->assign('"AlbumClass"', $pageClassname);
+                    $update->assign('"PhotoGalleryPageID"', 0);
+                    $update->execute();
+                    $updatecount++;
+                }
+            }
+            if(isset($row['PhotoGalleryBlockID']) && $row['PhotoGalleryBlockID']) {
+                $update = SQLUpdate::create('"PhotoGalleryImage"')->addWhere(['ID' => $row['ID']]);
+                $update->assign('"AlbumID"', $row['PhotoGalleryBlockID']);
+                $update->assign('"AlbumClass"', "PurpleSpider\ElementalBasicGallery\ImageGalleryBlock");
+                $update->assign('"PhotoGalleryBlockID"', 0);
+                $update->execute();
+                $updatecount++;
+            }
+        }
+
+        echo($updatecount." records updated.");
+
+    }
+
+}