From 4f01b09ded8a0aa21f273596051ca8f32426bef2 Mon Sep 17 00:00:00 2001
From: Charles Haley <>
Date: Sat, 11 Sep 2010 09:21:29 +0100
Subject: [PATCH 1/2] Check in the metadata class that custom field names begin
 with '#'

---
 src/calibre/ebooks/metadata/book/base.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/calibre/ebooks/metadata/book/base.py b/src/calibre/ebooks/metadata/book/base.py
index 69a3c42f4d..d0b428bf96 100644
--- a/src/calibre/ebooks/metadata/book/base.py
+++ b/src/calibre/ebooks/metadata/book/base.py
@@ -156,6 +156,9 @@ class Metadata(object):
         the key name not the label
         '''
         if field is not None:
+            if not field.startswith('#'):
+                raise AttributeError(
+                        'Custom field name %s must begin with \'#\''%repr(field))
             if metadata is None:
                 traceback.print_stack()
             metadata = copy.deepcopy(metadata)

From afe5546a15aa34fec849c875cb2b9b139c36ebd6 Mon Sep 17 00:00:00 2001
From: Charles Haley <>
Date: Sat, 11 Sep 2010 09:23:03 +0100
Subject: [PATCH 2/2] Avoid spurious exceptions when adding None custom
 metadata

---
 src/calibre/ebooks/metadata/book/base.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/calibre/ebooks/metadata/book/base.py b/src/calibre/ebooks/metadata/book/base.py
index d0b428bf96..be9a4675c0 100644
--- a/src/calibre/ebooks/metadata/book/base.py
+++ b/src/calibre/ebooks/metadata/book/base.py
@@ -161,6 +161,7 @@ class Metadata(object):
                         'Custom field name %s must begin with \'#\''%repr(field))
             if metadata is None:
                 traceback.print_stack()
+                return
             metadata = copy.deepcopy(metadata)
             if '#value#' not in metadata:
                 if metadata['datatype'] == 'text' and metadata['is_multiple']: