From 7571cbf7acc5f3fe2afe82bcedb97565bb97bfc2 Mon Sep 17 00:00:00 2001
From: Charles Haley <>
Date: Thu, 20 Sep 2012 08:30:10 +0200
Subject: [PATCH] Make approximate_formats work when there are no formats

---
 src/calibre/utils/formatter_functions.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/calibre/utils/formatter_functions.py b/src/calibre/utils/formatter_functions.py
index fae2d50f80..393ef876c9 100644
--- a/src/calibre/utils/formatter_functions.py
+++ b/src/calibre/utils/formatter_functions.py
@@ -608,6 +608,8 @@ class BuiltinApproximateFormats(BuiltinFormatterFunction):
 
     def evaluate(self, formatter, kwargs, mi, locals):
         fmt_data = mi.get('db_approx_formats', [])
+        if not fmt_data:
+            return ''
         data = sorted(fmt_data)
         return ','.join(v.upper() for v in data)