Fix complex multisort in Python 3.

CHANGES.rst

@@ -21,6 +21,7 @@ Changelog
 - Fix bugs with ``<dtml-in>``:
 
     - Raise proper error if prefix is not simple.
+    - Fix complex multisort in Python 3.
 
 
 3.0b4 (2018-07-12)

src/DocumentTemplate/DT_In.py

@@ -333,6 +333,7 @@
 from operator import itemgetter
 import sys
 import re
+import functools
 
 from DocumentTemplate.DT_Util import ParseError, parse_params, name_param
 from DocumentTemplate.DT_Util import str, join_unicode
@@ -836,7 +837,7 @@ def sort_sequence(self, sequence, md):
 
         if need_sortfunc:
             by = SortBy(multsort, sf_list)
-            s.sort(by)
+            s.sort(key=functools.cmp_to_key(by))
         else:
             # In python 3 a key is required when tuples in the list have
             # the same sort key to prevent attempting to compare the second

src/DocumentTemplate/tests/test_DT_In.py

@@ -7,6 +7,13 @@ class DummySection(object):
     blocks = ['dummy']
 
 
+class Dummy(object):
+    """Dummy with attribute"""
+
+    def __init__(self, name, number=0):
+        self.name = name
+        self.number = number
+
 class TestIn(unittest.TestCase):
     """Testing ..DT_in.InClass."""
 
@@ -54,4 +61,72 @@ def test_DT_In__InClass____init__1(self):
             '<dtml-var sequence-item>'
             '</dtml-in>')
         with self.assertRaisesRegexp(ParseError, '^prefix is not a simple '):
-                html(seq=sequence)
+                html(seq=sequence)
+
+    def test_DT_In__InClass__renderwob__06(self):
+        """It allows multisort."""
+        seq = [Dummy('alberta', 2), Dummy('alberta', 1), Dummy('barnie', 1)]
+        html = self.doc_class(
+            '<dtml-in seq sort="name,number">'
+            'Item <dtml-var sequence-number>: '
+            '<dtml-var sequence-var-name> , <dtml-var sequence-var-number>'
+            '</dtml-in>')
+        res = html(seq=seq)
+        expected = (
+            'Item 1: alberta , 1'
+            'Item 2: alberta , 2'
+            'Item 3: barnie , 1')
+        self.assertEqual(res, expected)
+        html = self.doc_class(
+            '<dtml-in seq sort="number,name">'
+            'Item <dtml-var sequence-number>: '
+            '<dtml-var sequence-var-name> , <dtml-var sequence-var-number>'
+            '</dtml-in>')
+        res = html(seq=seq)
+        expected = (
+            'Item 1: alberta , 1'
+            'Item 2: barnie , 1'
+            'Item 3: alberta , 2')
+        self.assertEqual(res, expected)
+
+    def test_DT_In__InClass__renderwob__07(self):
+        """It allows complex multisort. Smoke test."""
+        # This test also covers most of `SortBy`.
+        seq = [Dummy('alberta', 2), Dummy('alberta', 1), Dummy('barnie', 1)]
+        html = self.doc_class(
+            '<dtml-in seq sort="name/nocase/asc,number/cmp/desc">'
+            'Item <dtml-var sequence-number>: '
+            '<dtml-var sequence-var-name> , <dtml-var sequence-var-number>'
+            '</dtml-in>')
+        res = html(seq=seq)
+        expected = (
+            'Item 1: alberta , 2'
+            'Item 2: alberta , 1'
+            'Item 3: barnie , 1')
+        self.assertEqual(res, expected)
+        # It can sort the other way round
+        html = self.doc_class(
+            '<dtml-in seq sort="number/cmp/asc,name/strcoll/desc">'
+            'Item <dtml-var sequence-number>: '
+            '<dtml-var sequence-var-name> , <dtml-var sequence-var-number>'
+            '</dtml-in>')
+        res = html(seq=seq)
+        expected = (
+            'Item 1: barnie , 1'
+            'Item 2: alberta , 1'
+            'Item 3: alberta , 2')
+        self.assertEqual(res, expected)
+        # It is possible to omit parts of complex sort.
+        seq.append(Dummy('alberta', 1))
+        html = self.doc_class(
+            '<dtml-in seq sort="number,name/strcoll_nocase">'
+            'Item <dtml-var sequence-number>: '
+            '<dtml-var sequence-var-name> , <dtml-var sequence-var-number>'
+            '</dtml-in>')
+        res = html(seq=seq)
+        expected = (
+            'Item 1: alberta , 1'
+            'Item 2: alberta , 1'
+            'Item 3: barnie , 1'
+            'Item 4: alberta , 2')
+        self.assertEqual(res, expected)