PYTHON-1326 Remove the "useCursor" aggregate option (#560)

Author: ShaneHarvey

doc/changelog.rst

@@ -36,6 +36,8 @@ Breaking Changes in 4.0
 - Removed :meth:`pymongo.collection.Collection.remove`.
 - Removed :meth:`pymongo.collection.Collection.find_and_modify`.
 - Removed :meth:`pymongo.collection.Collection.group`.
+- Removed the ``useCursor`` option for
+  :meth:`~pymongo.collection.Collection.aggregate`.
 - Removed :meth:`pymongo.mongo_client.MongoClient.close_cursor`. Use
   :meth:`pymongo.cursor.Cursor.close` instead.
 - Removed :meth:`pymongo.mongo_client.MongoClient.kill_cursors`.

doc/migrate-to-pymongo4.rst

@@ -140,6 +140,14 @@ can be changed to this::
 Collection
 ----------
 
+The useCursor option for Collection.aggregate is removed
+........................................................
+
+Removed the ``useCursor`` option for
+:meth:`~pymongo.collection.Collection.aggregate` which was deprecated in
+PyMongo 3.6. The option was only necessary when upgrading from MongoDB 2.4
+to MongoDB 2.6.
+
 Collection.insert is removed
 ............................
 

pymongo/aggregation.py

@@ -169,15 +169,6 @@ def get_cursor(self, session, server, sock_info, slave_ok):
 
 
 class _CollectionAggregationCommand(_AggregationCommand):
-    def __init__(self, *args, **kwargs):
-        # Pop additional option and initialize parent class.
-        use_cursor = kwargs.pop("use_cursor", True)
-        super(_CollectionAggregationCommand, self).__init__(*args, **kwargs)
-
-        # Remove the cursor document if the user has set use_cursor to False.
-        self._use_cursor = use_cursor
-        if not self._use_cursor:
-            self._options.pop("cursor", None)
 
     @property
     def _aggregation_target(self):
@@ -201,7 +192,7 @@ def __init__(self, *args, **kwargs):
         super(_CollectionRawAggregationCommand, self).__init__(*args, **kwargs)
 
         # For raw-batches, we set the initial batchSize for the cursor to 0.
-        if self._use_cursor and not self._performs_write:
+        if not self._performs_write:
             self._options["cursor"]["batchSize"] = 0
 
 

pymongo/collection.py

@@ -2124,19 +2124,9 @@ def options(self, session=None):
 
     def _aggregate(self, aggregation_command, pipeline, cursor_class, session,
                    explicit_session, **kwargs):
-        # Remove things that are not command options.
-        use_cursor = True
-        if "useCursor" in kwargs:
-            warnings.warn(
-                "The useCursor option is deprecated "
-                "and will be removed in PyMongo 4.0",
-                DeprecationWarning, stacklevel=2)
-            use_cursor = common.validate_boolean(
-                "useCursor", kwargs.pop("useCursor", True))
-
         cmd = aggregation_command(
             self, cursor_class, pipeline, kwargs, explicit_session,
-            user_fields={'cursor': {'firstBatch': 1}}, use_cursor=use_cursor)
+            user_fields={'cursor': {'firstBatch': 1}})
         return self.__database.client._retryable_read(
             cmd.get_cursor, cmd.get_read_preference(session), session,
             retryable=not cmd._performs_write)
@@ -2155,13 +2145,10 @@ def aggregate(self, pipeline, session=None, **kwargs):
           - `maxTimeMS` (int): The maximum amount of time to allow the operation
             to run in milliseconds.
           - `batchSize` (int): The maximum number of documents to return per
-            batch. Ignored if the connected mongod or mongos does not support
-            returning aggregate results using a cursor, or `useCursor` is
-            ``False``.
+            batch.
           - `collation` (optional): An instance of
             :class:`~pymongo.collation.Collation`. This option is only supported
             on MongoDB 3.4 and above.
-          - `useCursor` (bool): Deprecated. Will be removed in PyMongo 4.0.
 
         The :meth:`aggregate` method obeys the :attr:`read_preference` of this
         :class:`Collection`, except when ``$out`` or ``$merge`` are used, in
@@ -2186,6 +2173,8 @@ def aggregate(self, pipeline, session=None, **kwargs):
           A :class:`~pymongo.command_cursor.CommandCursor` over the result
           set.
 
+        .. versionchanged:: 4.0
+           Removed the ``useCursor`` option.
         .. versionchanged:: 3.9
            Apply this collection's read concern to pipelines containing the
            `$out` stage when connected to MongoDB >= 4.2.

test/test_collection.py

@@ -1615,12 +1615,7 @@ def test_aggregate(self):
         self.assertRaises(TypeError, db.test.aggregate, "wow")
 
         pipeline = {"$project": {"_id": False, "foo": True}}
-        # MongoDB 3.5.1+ requires either the 'cursor' or 'explain' options.
-        if client_context.version.at_least(3, 5, 1):
-            result = db.test.aggregate([pipeline])
-        else:
-            result = db.test.aggregate([pipeline], useCursor=False)
-
+        result = db.test.aggregate([pipeline])
         self.assertTrue(isinstance(result, CommandCursor))
         self.assertEqual([{'foo': [1, 2]}], list(result))
 
@@ -1639,11 +1634,7 @@ def test_aggregate_raw_bson(self):
         coll = db.get_collection(
             'test',
             codec_options=CodecOptions(document_class=RawBSONDocument))
-        # MongoDB 3.5.1+ requires either the 'cursor' or 'explain' options.
-        if client_context.version.at_least(3, 5, 1):
-            result = coll.aggregate([pipeline])
-        else:
-            result = coll.aggregate([pipeline], useCursor=False)
+        result = coll.aggregate([pipeline])
         self.assertTrue(isinstance(result, CommandCursor))
         first_result = next(result)
         self.assertIsInstance(first_result, RawBSONDocument)
@@ -1655,9 +1646,6 @@ def test_aggregation_cursor_validation(self):
         cursor = db.test.aggregate([projection], cursor={})
         self.assertTrue(isinstance(cursor, CommandCursor))
 
-        cursor = db.test.aggregate([projection], useCursor=True)
-        self.assertTrue(isinstance(cursor, CommandCursor))
-
     def test_aggregation_cursor(self):
         db = self.db
         if client_context.has_secondaries: