fixed bug #1280295 'Enable natural sorting for song book searches' --fixes 1280294

openlp/plugins/songs/lib/mediaitem.py

@@ -255,7 +255,7 @@ class SongMediaItem(MediaManagerItem):
         log.debug('display results Book')
         self.list_view.clear()
         for book in search_results:
-            songs = sorted(book.songs, key=lambda song: int(re.match(r'[0-9]+', '0' + song.song_number).group()))
+            songs = sorted(book.songs, key=lambda song: self._natural_sort_key(song.song_number))
             for song in songs:
                 # Do not display temporary songs
                 if song.temporary:
@@ -583,6 +583,24 @@ class SongMediaItem(MediaManagerItem):
         # List must be empty at the end
         return not author_list
 
+    def _try_int(self, s):
+        """
+        Convert string s to an integer if possible. Fail silently and return
+        the string as-is if it isn't an integer.
+        :param s: The string to try to convert.
+        """
+        try:
+            return int(s)
+        except (TypeError, ValueError):
+            return s
+
+    def _natural_sort_key(self, s):
+        """
+        Return a tuple by which s is sorted.
+        :param s: A string value from the list we want to sort.
+        """
+        return list(map(self._try_int, re.findall(r'(\d+|\D+)', s)))
+
     def search(self, string, show_error):
         """
         Search for some songs