Remove deprecated param + fix cursor snapshot feature

docs/changelog.rst

@@ -10,11 +10,13 @@ Development
 - Fixed a bug causing inaccurate query results, while combining ``__raw__`` and regular filters for the same field #2264
 - Add support for the `elemMatch` projection operator in .fields() (e.g BlogPost.objects.fields(elemMatch__comments="test")) #2267
 - DictField validate failed without default connection (bug introduced in 0.19.0) #2239
+- Fix cursor snapshot feature (`Doc.objects().snapshot(True)`), which was deprecated but is now working
 - Remove methods deprecated years ago:
-    - name parameter in Field constructor e.g `StringField(name="...")`, was replaced by db_field
+    - `name` parameter in Field constructor e.g `StringField(name="...")`, was replaced by db_field
     - Queryset.slave_okay() was deprecated since pymongo3
     - dropDups was dropped with MongoDB3
     - ``Queryset._ensure_indexes`` and ``Queryset.ensure_indexes``, the right method to use is ``Document.ensure_indexes``
+    - Remove `full_response` from ``Queryset.modify``, as it is not working with Pymongo 3+
 
 Changes in 0.19.1
 =================

mongoengine/queryset/base.py

@@ -600,9 +600,7 @@ def update_one(self, upsert=False, write_concern=None, full_result=False, **upda
             **update
         )
 
-    def modify(
-        self, upsert=False, full_response=False, remove=False, new=False, **update
-    ):
+    def modify(self, upsert=False, remove=False, new=False, **update):
         """Update and return the updated document.
 
         Returns either the document before or after modification based on `new`
@@ -616,8 +614,6 @@ def modify(
         information about the command's execution.
 
         :param upsert: insert if document doesn't exist (default ``False``)
-        :param full_response: return the entire response object from the
-            server (default ``False``, not available for PyMongo 3+)
         :param remove: remove rather than updating (default ``False``)
         :param new: return updated rather than original document
             (default ``False``)
@@ -639,9 +635,6 @@ def modify(
         sort = queryset._ordering
 
         try:
-            if full_response:
-                msg = "With PyMongo 3+, it is not possible anymore to get the full response."
-                warnings.warn(msg, DeprecationWarning)
             if remove:
                 result = queryset._collection.find_one_and_delete(
                     query, sort=sort, **self._cursor_args
@@ -664,14 +657,8 @@ def modify(
         except pymongo.errors.OperationFailure as err:
             raise OperationError(u"Update failed (%s)" % err)
 
-        if full_response:
-            if result["value"] is not None:
-                result["value"] = self._document._from_son(
-                    result["value"], only_fields=self.only_fields
-                )
-        else:
-            if result is not None:
-                result = self._document._from_son(result, only_fields=self.only_fields)
+        if result is not None:
+            result = self._document._from_son(result, only_fields=self.only_fields)
 
         return result
 
@@ -1151,10 +1138,7 @@ def snapshot(self, enabled):
         :param enabled: whether or not snapshot mode is enabled
 
         ..versionchanged:: 0.5 - made chainable
-        .. deprecated:: Ignored with PyMongo 3+
         """
-        msg = "snapshot is deprecated as it has no impact when using PyMongo 3+."
-        warnings.warn(msg, DeprecationWarning)
         queryset = self.clone()
         queryset._snapshot = enabled
         return queryset
@@ -1594,25 +1578,23 @@ def _collection(self):
 
     @property
     def _cursor_args(self):
-        fields_name = "projection"
-        # snapshot is not handled at all by PyMongo 3+
-        # TODO: evaluate similar possibilities using modifiers
-        if self._snapshot:
-            msg = "The snapshot option is not anymore available with PyMongo 3+"
-            warnings.warn(msg, DeprecationWarning)
+        projection_field_name = "projection"
 
         cursor_args = {}
         if not self._timeout:
             cursor_args["no_cursor_timeout"] = True
 
+        if self._snapshot:
+            cursor_args["modifiers"] = {"$snapshot": True}
+
         if self._loaded_fields:
-            cursor_args[fields_name] = self._loaded_fields.as_dict()
+            cursor_args[projection_field_name] = self._loaded_fields.as_dict()
 
         if self._search_text:
-            if fields_name not in cursor_args:
-                cursor_args[fields_name] = {}
+            if projection_field_name not in cursor_args:
+                cursor_args[projection_field_name] = {}
 
-            cursor_args[fields_name]["_text_score"] = {"$meta": "textScore"}
+            cursor_args[projection_field_name]["_text_score"] = {"$meta": "textScore"}
 
         return cursor_args
 

tests/queryset/test_queryset.py

@@ -5595,10 +5595,10 @@ def test_create_count(self):
         self.Person.objects.create(name="Baz")
         assert self.Person.objects.count(with_limit_and_skip=True) == 3
 
-        newPerson = self.Person.objects.create(name="Foo_1")
+        self.Person.objects.create(name="Foo_1")
         assert self.Person.objects.count(with_limit_and_skip=True) == 4
 
-    def test_no_cursor_timeout(self):
+    def test_cursor_args_no_cursor_timeout(self):
         qs = self.Person.objects()
         assert qs._cursor_args == {}  # ensure no regression of  #2148
 
@@ -5608,6 +5608,22 @@ def test_no_cursor_timeout(self):
         qs = self.Person.objects().timeout(False)
         assert qs._cursor_args == {"no_cursor_timeout": True}
 
+    def test_cursor_args_snapshot(self):
+        self.Person.drop_collection()
+        self.Person.objects.create(name="Foo")
+        self.Person.objects.create(name="Bar")
+        self.Person.objects.create(name="Baz")
+
+        qs = self.Person.objects()
+        assert qs._cursor_args == {}
+
+        qs = self.Person.objects().snapshot(False)
+        assert qs._cursor_args == {}
+
+        qs = self.Person.objects().snapshot(True)
+        assert qs._cursor_args == {"modifiers": {"$snapshot": True}}
+        assert len(list(qs)) == 3
+
 
 if __name__ == "__main__":
     unittest.main()