Index: field.class.php
===================================================================
RCS file: /cvsroot/moodle/moodle/mod/data/field/number/field.class.php,v
retrieving revision 1.6
diff -u -r1.6 field.class.php
--- mod/data/field/number/field.class.php	26 Feb 2007 06:56:08 -0000	1.6
+++ mod/data/field/number/field.class.php	12 May 2008 21:55:46 -0000
@@ -34,7 +34,12 @@
         $content = new object;
         $content->fieldid = $this->field->id;
         $content->recordid = $recordid;
-        $content->content = (float)$value;
+        $value = trim($value);
+        if (strlen($value) > 0) {
+            $content->content = floatval($value);
+        } else {
+            $content->content = null;
+        }
 
         if ($oldcontent = get_record('data_content','fieldid', $this->field->id, 'recordid', $recordid)) {
             $content->id = $oldcontent->id;