From 771e93ef18858a0a4ab1088d0678ce9e4fca75df Mon Sep 17 00:00:00 2001
From: Will Rossiter <will.rossiter@gmail.com>
Date: Mon, 23 May 2011 20:36:20 +1200
Subject: [PATCH] BUGFIX: return null data from checkbox field if not set.
 Fixes issue with validation using str_len() to determine valid field. FIXES:
 http://open.silverstripe.org/ticket/6231. Thanks natmchugh

---
 forms/CheckboxField.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/forms/CheckboxField.php b/forms/CheckboxField.php
index 0e5434f9c..8cbc2a92e 100755
--- a/forms/CheckboxField.php
+++ b/forms/CheckboxField.php
@@ -13,7 +13,7 @@ class CheckboxField extends FormField {
 	}
 
 	function dataValue() {
-		return ($this->value) ? 1 : 0;
+		return ($this->value) ? 1 : NULL;
 	}
 	
 	function Value() {