Implement collation for queryset

mongoengine/queryset/base.py

@@ -80,6 +80,7 @@ class BaseQuerySet(object):
         self._limit = None
         self._skip = None
         self._hint = -1  # Using -1 as None is a valid value for hint
+        self._collation = None
         self._batch_size = None
         self.only_fields = []
         self._max_time_ms = None
@@ -781,6 +782,7 @@ class BaseQuerySet(object):
             "_limit",
             "_skip",
             "_hint",
+            "_collation",
             "_auto_dereference",
             "_search_text",
             "only_fields",
@@ -863,6 +865,32 @@ class BaseQuerySet(object):
 
         return queryset
 
+    def collation(self, collation=None):
+        """
+        Collation allows users to specify language-specific rules for string
+        comparison, such as rules for lettercase and accent marks.
+        :param collation: `~pymongo.collation.Collation` or dict with
+        following fields:
+            {
+                locale: str,
+                caseLevel: bool,
+                caseFirst: str,
+                strength: int,
+                numericOrdering: bool,
+                alternate: str,
+                maxVariable: str,
+                backwards: str
+            }
+        Collation should be added to indexes like in test example
+        """
+        queryset = self.clone()
+        queryset._collation = collation
+
+        if queryset._cursor_obj:
+            queryset._cursor_obj.collation(collation)
+
+        return queryset
+
     def batch_size(self, size):
         """Limit the number of documents returned in a single batch (each
         batch requires a round trip to the server).
@@ -1636,6 +1664,9 @@ class BaseQuerySet(object):
         if self._hint != -1:
             self._cursor_obj.hint(self._hint)
 
+        if self._collation is not None:
+            self._cursor_obj.collation(self._collation)
+
         if self._batch_size is not None:
             self._cursor_obj.batch_size(self._batch_size)
 

tests/document/indexes.py

@@ -539,6 +539,35 @@ class IndexesTest(unittest.TestCase):
         with self.assertRaises(ValueError):
             BlogPost.objects.hint(("tags", 1)).count()
 
+    def test_collation(self):
+        base = {'locale': "en", 'strength': 2}
+
+        class BlogPost(Document):
+            name = StringField()
+            meta = {"indexes": [
+                {"fields": ["name"], "name": 'name_index',
+                 'collation': base}
+            ]}
+
+        BlogPost.drop_collection()
+
+        names = tuple("%sag %i" % ('t' if n % 2 == 0 else 'T', n) for n in range(10))
+        for name in names:
+            BlogPost(name=name).save()
+
+        query_result = BlogPost.objects.collation(base).order_by('name')
+        self.assertEqual([x.name for x in query_result],
+                         sorted(names, key=lambda x: x.lower()))
+        self.assertEqual(10, query_result.count())
+
+        incorrect_collation = {'arndom': 'wrdo'}
+        with self.assertRaises(OperationFailure):
+            BlogPost.objects.collation(incorrect_collation).count()
+
+        query_result = BlogPost.objects.collation({}).order_by('name')
+        self.assertEqual([x.name for x in query_result],
+                         sorted(names))
+
     def test_unique(self):
         """Ensure that uniqueness constraints are applied to fields.
         """