From 1423e94c130b6e7996e59df2115e47dec8223b09 Mon Sep 17 00:00:00 2001
From: Charles Haley <>
Date: Sat, 24 Sep 2011 12:56:37 +0200
Subject: [PATCH] Make get_components use precomputed values for composite
 columns. Improves performance and makes values computed with user-defined
 functions work.

---
 src/calibre/library/save_to_disk.py | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/calibre/library/save_to_disk.py b/src/calibre/library/save_to_disk.py
index aebb853805..7b8ff11d16 100644
--- a/src/calibre/library/save_to_disk.py
+++ b/src/calibre/library/save_to_disk.py
@@ -150,12 +150,21 @@ class Formatter(TemplateFormatter):
                 traceback.print_exc()
                 b = None
             if b is not None and b['datatype'] == 'composite':
+                val = b.get('#value#', None)
+                if val is not None:
+                    return val.replace('/', '_').replace('\\', '_')
                 if key in self.composite_values:
+                    self.composite_values[key] = val
                     return self.composite_values[key]
-                self.composite_values[key] = 'RECURSIVE_COMPOSITE FIELD (S2D) ' + key
-                self.composite_values[key] = \
-                    self.vformat(b['display']['composite_template'], [], kwargs)
-                return self.composite_values[key]
+                try:
+                    # We really should not get here, but it is safer to try
+                    self.composite_values[key] = 'RECURSIVE_COMPOSITE FIELD (S2D) ' + key
+                    self.composite_values[key] = \
+                        self.vformat(b['display']['composite_template'],
+                                     [], kwargs).replace('/', '_').replace('\\', '_')
+                    return self.composite_values[key]
+                except Exception, e:
+                    return unicode(e)
             if key in kwargs:
                 val = kwargs[key]
                 if isinstance(val, list):
@@ -170,6 +179,13 @@ def get_components(template, mi, id, timefmt='%b %Y', length=250,
         sanitize_func=ascii_filename, replace_whitespace=False,
         to_lowercase=False, safe_format=True):
 
+    # Note: the mi argument is assumed to be an instance of Metadata returned
+    # by db.get_metadata(). Reason: the composite columns should have already
+    # been evaluated, which get_metadata does. If the mi is something else and
+    # if the template uses composite columns, then a best-efforts attempt is
+    # made to evaluate them. This will fail if the template uses a user-defined
+    # template function.
+
     tsorder = tweaks['save_template_title_series_sorting']
     format_args = FORMAT_ARGS.copy()
     format_args.update(mi.all_non_none_fields())