From c6dadb71008012dcc263ab0ea31f7bdabf352e09 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Wed, 11 Dec 2013 22:34:41 +0530
Subject: [PATCH] Cover grid: Fix text showing 'None' for rating fields for
 books with no rating

---
 src/calibre/gui2/library/alternate_views.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/calibre/gui2/library/alternate_views.py b/src/calibre/gui2/library/alternate_views.py
index a797916c49..b09bec64c8 100644
--- a/src/calibre/gui2/library/alternate_views.py
+++ b/src/calibre/gui2/library/alternate_views.py
@@ -379,8 +379,8 @@ class CoverDelegate(QStyledItemDelegate):
                 mi = db.get_proxy_metadata(book_id)
                 display_name, ans, val, fm = mi.format_field_extended(field)
                 if fm and fm['datatype'] == 'rating':
-                    ans = u'\u2605' * int(val/2.0)
-            return unicode(ans)
+                    ans = u'\u2605' * int(val/2.0) if val is not None else ''
+            return '' if ans is None else unicode(ans)
         except Exception:
             if DEBUG:
                 import traceback