Fix gallery merging: support for None offsets

[redakcja.git] / apps / catalogue / models / book.py

diff --git a/apps/catalogue/models/book.py b/apps/catalogue/models/book.py
index 25b9304..4d1b12e 100755 (executable)
--- a/apps/catalogue/models/book.py
+++ b/apps/catalogue/models/book.py
@@ -205,7 +205,8 @@ class Book(models.Model):
         # and move the gallery starts
         if gm.was_merged:
                 for chunk in self[len(self) - len_other:]:
-                        chunk.gallery_start += gm.dest_size - gm.num_deleted
+                        old_start = chunk.gallery_start or 1
+                        chunk.gallery_start = old_start + gm.dest_size - gm.num_deleted
                         chunk.save()
 
         other.delete()
@@ -270,6 +271,14 @@ class Book(models.Model):
         valid_about = self.correct_about()
         assert bi.about == valid_about, _("rdf:about is not") + " " + valid_about
 
+    def publishable_error(self):
+        try:
+            return self.assert_publishable()
+        except AssertionError, e:
+            return e
+        else:
+            return None
+
     def hidden(self):
         return self.slug.startswith('.')