From 1770fab206cc9ff6ddd8fee3f421d2b7a865964f Mon Sep 17 00:00:00 2001
From: Damian Mooyman <damian@silverstripe.com>
Date: Mon, 9 Mar 2015 11:44:39 +1300
Subject: [PATCH] BUG Fix gridfield generating invalid session keys

---
 forms/gridfield/GridField.php | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/forms/gridfield/GridField.php b/forms/gridfield/GridField.php
index 4c82f4e78..43bfc9b02 100644
--- a/forms/gridfield/GridField.php
+++ b/forms/gridfield/GridField.php
@@ -840,7 +840,8 @@ class GridField_FormAction extends FormAction {
 			'args' => $this->args,
 		);
 
-		$id = substr(md5(serialize($state)), 0, 8);
+		// Ensure $id doesn't contain only numeric characters
+		$id = 'gf_'.substr(md5(serialize($state)), 0, 8);
 		Session::set($id, $state);
 		$actionData['StateID'] = $id;