From 96676fc7153685b271fa761611dab6dbc5a43599 Mon Sep 17 00:00:00 2001
From: Charles Haley <cbhaley@i.wont.say.com>
Date: Sat, 9 Mar 2024 11:40:02 +0000
Subject: [PATCH] Fix formatter function book_values() not to ignore empty
 strings or zero values.

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

diff --git a/src/calibre/utils/formatter_functions.py b/src/calibre/utils/formatter_functions.py
index bbe9c3a56e..c4adfa9750 100644
--- a/src/calibre/utils/formatter_functions.py
+++ b/src/calibre/utils/formatter_functions.py
@@ -2453,7 +2453,7 @@ class BuiltinBookValues(BuiltinFormatterFunction):
                 f = db.new_api.get_proxy_metadata(id_).get(column, None)
                 if isinstance(f, (tuple, list)):
                     s.update(f)
-                elif f:
+                elif f is not None:
                     s.add(str(f))
             return sep.join(s)
         except Exception as e: