--- a/web/views/navigation.py	Mon Oct 19 20:22:01 2009 +0200
+++ b/web/views/navigation.py	Wed Oct 21 17:32:20 2009 +0200
@@ -62,6 +62,8 @@
         req = self._cw
         if attrname is not None:
             def index_display(row):
+                if not rset[row][col]: # outer join
+                    return u''
                 entity = rset.get_entity(row, col)
                 return entity.printable_value(attrname, format='text/plain')
         elif self._cw.schema.eschema(rset.description[0][col]).final: