fix string in natural sort and move db

openlp/core/utils/__init__.py

@@ -523,13 +523,15 @@ def get_locale_key(string):
 def get_natural_key(string):
     """
     Generate a key for locale aware natural string sorting.
+
+    :param string: string to be sorted by
     Returns a list of string compare keys and integers.
     """
     key = DIGITS_OR_NONDIGITS.findall(string)
     key = [int(part) if part.isdigit() else get_locale_key(part) for part in key]
     # Python 3 does not support comparison of different types anymore. So make sure, that we do not compare str
     # and int.
-    if string[0].isdigit():
+    if string and string[0].isdigit():
         return [b''] + key
     return key
 

openlp/plugins/songs/lib/upgrade.py

@@ -28,8 +28,8 @@ import logging
 from sqlalchemy import Table, Column, ForeignKey, types
 from sqlalchemy.sql.expression import func, false, null, text
 
+from openlp.core.common.db import drop_columns
 from openlp.core.lib.db import get_upgrade_op
-from openlp.core.utils.db import drop_columns
 
 log = logging.getLogger(__name__)
 __version__ = 5

tests/functional/openlp_core/test_db.py

@@ -22,17 +22,17 @@
 """
 Package to test the openlp.core.utils.db package.
 """
-from tempfile import mkdtemp
-from unittest import TestCase
 import gc
 import os
 import shutil
-import sqlalchemy
 import time
+from tempfile import mkdtemp
+from unittest import TestCase
 
-from openlp.core.utils.db import drop_column, drop_columns
+import sqlalchemy
+
+from openlp.core.common.db import drop_column, drop_columns
 from openlp.core.lib.db import init_db, get_upgrade_op
-
 from tests.utils.constants import TEST_RESOURCES_PATH