From d73846213977b2fb1e382b38d86406bdf9a7e81f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastien=20G=C3=A9rard?= <bastien.gerard@cluepoints.com>
Date: Sat, 11 Jan 2020 23:15:30 +0100
Subject: [PATCH 01/11] Fix bug introduced in -1.19 related to DictField
 validate failing without default connection

---
 docs/changelog.rst              |  5 ++++
 mongoengine/fields.py           | 14 +++++-----
 mongoengine/mongodb_support.py  |  2 +-
 tests/fields/test_dict_field.py | 48 ++++++++++++++++++++-------------
 4 files changed, 42 insertions(+), 27 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index b8e6ae56..2b532da9 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -7,6 +7,11 @@ Development
 ===========
 - (Fill this out as you fix issues and develop your features).
 
+Changes in 0.19.2
+=================
+- DictField validate failed without default connection (bug introduced in 0.19.0) #2239
+
+
 Changes in 0.19.1
 =================
 - Requires Pillow < 7.0.0 as it dropped Python2 support
diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index 7ec8c0f3..d502dba3 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -1088,14 +1088,12 @@ class DictField(ComplexBaseField):
             msg = "Invalid dictionary key - documents must have only string keys"
             self.error(msg)
 
-        curr_mongo_ver = get_mongodb_version()
-
-        if curr_mongo_ver < MONGODB_36 and key_has_dot_or_dollar(value):
-            self.error(
-                'Invalid dictionary key name - keys may not contain "."'
-                ' or startswith "$" characters'
-            )
-        elif curr_mongo_ver >= MONGODB_36 and key_starts_with_dollar(value):
+        # Following condition applies to MongoDB >= 3.6
+        # older Mongo has stricter constraints but
+        # it will be rejected upon insertion anyway
+        # Having a validation that depends on the MongoDB version
+        # is not straightforward as the field isn't aware of the connected Mongo
+        if key_starts_with_dollar(value):
             self.error(
                 'Invalid dictionary key name - keys may not startswith "$" characters'
             )
diff --git a/mongoengine/mongodb_support.py b/mongoengine/mongodb_support.py
index 5d437fef..522f064e 100644
--- a/mongoengine/mongodb_support.py
+++ b/mongoengine/mongodb_support.py
@@ -11,7 +11,7 @@ MONGODB_36 = (3, 6)
 
 
 def get_mongodb_version():
-    """Return the version of the connected mongoDB (first 2 digits)
+    """Return the version of the default connected mongoDB (first 2 digits)
 
     :return: tuple(int, int)
     """
diff --git a/tests/fields/test_dict_field.py b/tests/fields/test_dict_field.py
index 44e628f6..6850cd58 100644
--- a/tests/fields/test_dict_field.py
+++ b/tests/fields/test_dict_field.py
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 import pytest
+from bson import InvalidDocument
 
 from mongoengine import *
 from mongoengine.base import BaseDict
@@ -19,22 +20,24 @@ class TestDictField(MongoDBTestCase):
         post = BlogPost(info=info).save()
         assert get_as_pymongo(post) == {"_id": post.id, "info": info}
 
-    def test_general_things(self):
-        """Ensure that dict types work as expected."""
+    def test_validate_invalid_type(self):
+        class BlogPost(Document):
+            info = DictField()
 
+        BlogPost.drop_collection()
+
+        invalid_infos = ["my post", ["test", "test"], {1: "test"}]
+        for invalid_info in invalid_infos:
+            with pytest.raises(ValidationError):
+                BlogPost(info=invalid_info).validate()
+
+    def test_keys_with_dots_or_dollars(self):
         class BlogPost(Document):
             info = DictField()
 
         BlogPost.drop_collection()
 
         post = BlogPost()
-        post.info = "my post"
-        with pytest.raises(ValidationError):
-            post.validate()
-
-        post.info = ["test", "test"]
-        with pytest.raises(ValidationError):
-            post.validate()
 
         post.info = {"$title": "test"}
         with pytest.raises(ValidationError):
@@ -48,25 +51,34 @@ class TestDictField(MongoDBTestCase):
         with pytest.raises(ValidationError):
             post.validate()
 
-        post.info = {1: "test"}
-        with pytest.raises(ValidationError):
-            post.validate()
-
         post.info = {"nested": {"the.title": "test"}}
         if get_mongodb_version() < MONGODB_36:
-            with pytest.raises(ValidationError):
-                post.validate()
+            # MongoDB < 3.6 rejects dots
+            # To avoid checking the mongodb version from the DictField class
+            # we rely on MongoDB to reject the data during the save
+            post.validate()
+            with pytest.raises(InvalidDocument):
+                post.save()
         else:
             post.validate()
 
         post.info = {"dollar_and_dot": {"te$st.test": "test"}}
         if get_mongodb_version() < MONGODB_36:
-            with pytest.raises(ValidationError):
-                post.validate()
+            post.validate()
+            with pytest.raises(InvalidDocument):
+                post.save()
         else:
             post.validate()
 
-        post.info = {"title": "test"}
+    def test_general_things(self):
+        """Ensure that dict types work as expected."""
+
+        class BlogPost(Document):
+            info = DictField()
+
+        BlogPost.drop_collection()
+
+        post = BlogPost(info={"title": "test"})
         post.save()
 
         post = BlogPost()

From 450658d7ac2b26be7849f8f0599fff06bb7e6ebc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastien=20G=C3=A9rard?= <bastien.gerard@cluepoints.com>
Date: Tue, 4 Feb 2020 22:51:02 +0100
Subject: [PATCH 02/11] fix indirect library version that dropped python2
 support recently

---
 setup.py | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/setup.py b/setup.py
index 5ba84e06..5cba5d9e 100644
--- a/setup.py
+++ b/setup.py
@@ -108,6 +108,10 @@ CLASSIFIERS = [
     "Topic :: Software Development :: Libraries :: Python Modules",
 ]
 
+PYTHON_VERSION = sys.version_info[0]
+PY3 = PYTHON_VERSION == 3
+PY2 = PYTHON_VERSION == 2
+
 extra_opts = {
     "packages": find_packages(exclude=["tests", "tests.*"]),
     "tests_require": [
@@ -116,9 +120,10 @@ extra_opts = {
         "coverage<5.0",  # recent coverage switched to sqlite format for the .coverage file which isn't handled properly by coveralls
         "blinker",
         "Pillow>=2.0.0, <7.0.0",  # 7.0.0 dropped Python2 support
+        "zipp<2.0.0",  # (dependency of pytest) dropped python2 support
     ],
 }
-if sys.version_info[0] == 3:
+if PY3:
     extra_opts["use_2to3"] = True
     if "test" in sys.argv:
         extra_opts["packages"] = find_packages()

From 4bca3de42f08a5ca4fdd0b4021d6a54f25e24003 Mon Sep 17 00:00:00 2001
From: Agustin Barto <abarto@gmail.com>
Date: Fri, 14 Feb 2020 16:43:07 -0300
Subject: [PATCH 03/11] Add support for the elemMatch projection operator. Add
 basic tests to the fields queryset method.

---
 mongoengine/queryset/base.py    |  2 +-
 tests/queryset/test_queryset.py | 51 +++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/mongoengine/queryset/base.py b/mongoengine/queryset/base.py
index 50cb37ac..710259df 100644
--- a/mongoengine/queryset/base.py
+++ b/mongoengine/queryset/base.py
@@ -1037,7 +1037,7 @@ class BaseQuerySet(object):
         """
 
         # Check for an operator and transform to mongo-style if there is
-        operators = ["slice"]
+        operators = ["slice", "elemMatch"]
         cleaned_fields = []
         for key, value in kwargs.items():
             parts = key.split("__")
diff --git a/tests/queryset/test_queryset.py b/tests/queryset/test_queryset.py
index b30350e6..5ebd545f 100644
--- a/tests/queryset/test_queryset.py
+++ b/tests/queryset/test_queryset.py
@@ -4476,6 +4476,57 @@ class TestQueryset(unittest.TestCase):
             expected = "[u'A1', u'A2']"
         assert expected == "%s" % sorted(names)
 
+    def test_fields(self):
+        class Bar(EmbeddedDocument):
+            v = StringField()
+            z = StringField()
+
+
+        class Foo(Document):
+            x = StringField()
+            y = IntField()
+            items = EmbeddedDocumentListField(Bar)
+
+
+        Foo.drop_collection()
+
+        Foo(x='foo1', y=1).save()
+        Foo(x='foo2', y=2, items=[]).save()
+        Foo(x='foo3', y=3, items=[Bar(z='a', v='V')]).save()
+        Foo(x='foo4', y=4, items=[Bar(z='a', v='V'), Bar(z='b', v='W'), Bar(z='b', v='X'), Bar(z='c', v='V')]).save()
+        Foo(x='foo5', y=5, items=[Bar(z='b', v='X'), Bar(z='c', v='V'), Bar(z='d', v='V'), Bar(z='e', v='V')]).save()
+
+        foos_with_x = list(Foo.objects.order_by('y').fields(x=1))
+
+        assert all(o.x is not None for o in foos_with_x)
+
+        foos_without_y = list(Foo.objects.order_by('y').fields(y=0))
+
+        assert all(o.y is None for o in foos_with_x)
+
+        foos_with_sliced_items = list(Foo.objects.order_by('y').fields(slice__items=1))
+
+        assert foos_with_sliced_items[0].items == []
+        assert foos_with_sliced_items[1].items == []
+        assert len(foos_with_sliced_items[2].items) == 1
+        assert foos_with_sliced_items[2].items[0].z == 'a'
+        assert len(foos_with_sliced_items[3].items) == 1
+        assert foos_with_sliced_items[3].items[0].z == 'a'
+        assert len(foos_with_sliced_items[4].items) == 1
+        assert foos_with_sliced_items[4].items[0].z == 'b'
+
+        foos_with_elem_match_items = list(Foo.objects.order_by('y').fields(elemMatch__items={'z': 'b'}))
+
+        assert foos_with_elem_match_items[0].items == []
+        assert foos_with_elem_match_items[1].items == []
+        assert foos_with_elem_match_items[2].items == []
+        assert len(foos_with_elem_match_items[3].items) == 1
+        assert foos_with_elem_match_items[3].items[0].z == 'b'
+        assert foos_with_elem_match_items[3].items[0].v == 'W'
+        assert len(foos_with_elem_match_items[4].items) == 1
+        assert foos_with_elem_match_items[4].items[0].z == 'b'
+
+
     def test_elem_match(self):
         class Foo(EmbeddedDocument):
             shape = StringField()

From 81f9b351b3838fe27924937e706300805e9eb82b Mon Sep 17 00:00:00 2001
From: Leonardo Domingues <leodmgs@gmail.com>
Date: Fri, 21 Feb 2020 19:14:34 -0300
Subject: [PATCH 04/11] Add return info in the save function docstring

---
 AUTHORS                 | 1 +
 mongoengine/document.py | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/AUTHORS b/AUTHORS
index b9a81c63..7d3000ce 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -255,3 +255,4 @@ that much better:
  * Filip Kucharczyk (https://github.com/Pacu2)
  * Eric Timmons (https://github.com/daewok)
  * Matthew Simpson (https://github.com/mcsimps2)
+ * Leonardo Domingues (https://github.com/leodmgs)
diff --git a/mongoengine/document.py b/mongoengine/document.py
index 23968f17..5e812510 100644
--- a/mongoengine/document.py
+++ b/mongoengine/document.py
@@ -332,7 +332,7 @@ class Document(six.with_metaclass(TopLevelDocumentMetaclass, BaseDocument)):
     ):
         """Save the :class:`~mongoengine.Document` to the database. If the
         document already exists, it will be updated, otherwise it will be
-        created.
+        created. Returns the saved object instance.
 
         :param force_insert: only try to create a new document, don't allow
             updates of existing documents.

From cfb4943986189a22ae75fd4f378f38f7ec0a77bb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastien=20G=C3=A9rard?= <bastien.gerard@cluepoints.com>
Date: Mon, 2 Mar 2020 22:49:21 +0100
Subject: [PATCH 05/11] reformat with black

---
 tests/queryset/test_queryset.py | 53 ++++++++++++++++++++++-----------
 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/tests/queryset/test_queryset.py b/tests/queryset/test_queryset.py
index 5ebd545f..f6d1a916 100644
--- a/tests/queryset/test_queryset.py
+++ b/tests/queryset/test_queryset.py
@@ -4481,51 +4481,68 @@ class TestQueryset(unittest.TestCase):
             v = StringField()
             z = StringField()
 
-
         class Foo(Document):
             x = StringField()
             y = IntField()
             items = EmbeddedDocumentListField(Bar)
 
-
         Foo.drop_collection()
 
-        Foo(x='foo1', y=1).save()
-        Foo(x='foo2', y=2, items=[]).save()
-        Foo(x='foo3', y=3, items=[Bar(z='a', v='V')]).save()
-        Foo(x='foo4', y=4, items=[Bar(z='a', v='V'), Bar(z='b', v='W'), Bar(z='b', v='X'), Bar(z='c', v='V')]).save()
-        Foo(x='foo5', y=5, items=[Bar(z='b', v='X'), Bar(z='c', v='V'), Bar(z='d', v='V'), Bar(z='e', v='V')]).save()
+        Foo(x="foo1", y=1).save()
+        Foo(x="foo2", y=2, items=[]).save()
+        Foo(x="foo3", y=3, items=[Bar(z="a", v="V")]).save()
+        Foo(
+            x="foo4",
+            y=4,
+            items=[
+                Bar(z="a", v="V"),
+                Bar(z="b", v="W"),
+                Bar(z="b", v="X"),
+                Bar(z="c", v="V"),
+            ],
+        ).save()
+        Foo(
+            x="foo5",
+            y=5,
+            items=[
+                Bar(z="b", v="X"),
+                Bar(z="c", v="V"),
+                Bar(z="d", v="V"),
+                Bar(z="e", v="V"),
+            ],
+        ).save()
 
-        foos_with_x = list(Foo.objects.order_by('y').fields(x=1))
+        foos_with_x = list(Foo.objects.order_by("y").fields(x=1))
 
         assert all(o.x is not None for o in foos_with_x)
 
-        foos_without_y = list(Foo.objects.order_by('y').fields(y=0))
+        foos_without_y = list(Foo.objects.order_by("y").fields(y=0))
 
         assert all(o.y is None for o in foos_with_x)
 
-        foos_with_sliced_items = list(Foo.objects.order_by('y').fields(slice__items=1))
+        foos_with_sliced_items = list(Foo.objects.order_by("y").fields(slice__items=1))
 
         assert foos_with_sliced_items[0].items == []
         assert foos_with_sliced_items[1].items == []
         assert len(foos_with_sliced_items[2].items) == 1
-        assert foos_with_sliced_items[2].items[0].z == 'a'
+        assert foos_with_sliced_items[2].items[0].z == "a"
         assert len(foos_with_sliced_items[3].items) == 1
-        assert foos_with_sliced_items[3].items[0].z == 'a'
+        assert foos_with_sliced_items[3].items[0].z == "a"
         assert len(foos_with_sliced_items[4].items) == 1
-        assert foos_with_sliced_items[4].items[0].z == 'b'
+        assert foos_with_sliced_items[4].items[0].z == "b"
 
-        foos_with_elem_match_items = list(Foo.objects.order_by('y').fields(elemMatch__items={'z': 'b'}))
+        foos_with_elem_match_items = list(
+            Foo.objects.order_by("y").fields(elemMatch__items={"z": "b"})
+        )
 
         assert foos_with_elem_match_items[0].items == []
         assert foos_with_elem_match_items[1].items == []
         assert foos_with_elem_match_items[2].items == []
         assert len(foos_with_elem_match_items[3].items) == 1
-        assert foos_with_elem_match_items[3].items[0].z == 'b'
-        assert foos_with_elem_match_items[3].items[0].v == 'W'
+        assert foos_with_elem_match_items[3].items[0].z == "b"
+        assert foos_with_elem_match_items[3].items[0].v == "W"
         assert len(foos_with_elem_match_items[4].items) == 1
-        assert foos_with_elem_match_items[4].items[0].z == 'b'
-
+        assert foos_with_elem_match_items[4].items[0].z == "b"
 
     def test_elem_match(self):
         class Foo(EmbeddedDocument):

From d287f480e5016090384650515c9342c767c4bbb7 Mon Sep 17 00:00:00 2001
From: Filip Kucharczyk <filip.m.kucharczyk@gmail.com>
Date: Tue, 4 Feb 2020 12:35:03 +0100
Subject: [PATCH 06/11] Fix for combining raw and regular filters

---
 mongoengine/queryset/transform.py | 4 ++--
 tests/queryset/test_transform.py  | 6 ++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/mongoengine/queryset/transform.py b/mongoengine/queryset/transform.py
index 0b73e99b..659a97e2 100644
--- a/mongoengine/queryset/transform.py
+++ b/mongoengine/queryset/transform.py
@@ -169,9 +169,9 @@ def query(_doc_cls=None, **kwargs):
 
         key = ".".join(parts)
 
-        if op is None or key not in mongo_query:
+        if key not in mongo_query:
             mongo_query[key] = value
-        elif key in mongo_query:
+        else:
             if isinstance(mongo_query[key], dict) and isinstance(value, dict):
                 mongo_query[key].update(value)
                 # $max/minDistance needs to come last - convert to SON
diff --git a/tests/queryset/test_transform.py b/tests/queryset/test_transform.py
index 3898809e..8d6c2d06 100644
--- a/tests/queryset/test_transform.py
+++ b/tests/queryset/test_transform.py
@@ -24,6 +24,12 @@ class TestTransform(unittest.TestCase):
         }
         assert transform.query(friend__age__gte=30) == {"friend.age": {"$gte": 30}}
         assert transform.query(name__exists=True) == {"name": {"$exists": True}}
+        assert transform.query(name=["Mark"], __raw__={"name": {"$in": "Tom"}}) == {
+            "$and": [{"name": ["Mark"]}, {"name": {"$in": "Tom"}}]
+        }
+        assert transform.query(name__in=["Tom"], __raw__={"name": "Mark"}) == {
+            "$and": [{"name": {"$in": ["Tom"]}}, {"name": "Mark"}]
+        }
 
     def test_transform_update(self):
         class LisDoc(Document):

From fda2e2b47ab5085b6ff5b6e27b40794a3fa9e77f Mon Sep 17 00:00:00 2001
From: Filip Kucharczyk <filip.m.kucharczyk@gmail.com>
Date: Tue, 4 Feb 2020 12:58:25 +0100
Subject: [PATCH 07/11] Update changelog

---
 docs/changelog.rst | 1 +
 1 file changed, 1 insertion(+)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index d924a2c1..8dcea62a 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -7,6 +7,7 @@ Development
 ===========
 - (Fill this out as you fix issues and develop your features).
 - Add Mongo 4.0 to Travis
+- Fixed a bug causing inaccurate query results, while combining ``__raw__`` and regular filters for the same field #2264
 
 Changes in 0.19.1
 =================

From aa4a6ae0234be23f237f68c3061f9db28c274741 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastien=20G=C3=A9rard?= <bastien.gerard@cluepoints.com>
Date: Sun, 15 Mar 2020 21:02:44 +0100
Subject: [PATCH 08/11] Fix invalid escape seq in codebase

---
 mongoengine/document.py                     | 2 +-
 mongoengine/queryset/base.py                | 6 +++---
 tests/fields/test_complex_datetime_field.py | 4 ++--
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/mongoengine/document.py b/mongoengine/document.py
index 5e812510..3cc0046e 100644
--- a/mongoengine/document.py
+++ b/mongoengine/document.py
@@ -56,7 +56,7 @@ class InvalidCollectionError(Exception):
 
 
 class EmbeddedDocument(six.with_metaclass(DocumentMetaclass, BaseDocument)):
-    """A :class:`~mongoengine.Document` that isn't stored in its own
+    r"""A :class:`~mongoengine.Document` that isn't stored in its own
     collection.  :class:`~mongoengine.EmbeddedDocument`\ s should be used as
     fields on :class:`~mongoengine.Document`\ s through the
     :class:`~mongoengine.EmbeddedDocumentField` field type.
diff --git a/mongoengine/queryset/base.py b/mongoengine/queryset/base.py
index 50cb37ac..7941e970 100644
--- a/mongoengine/queryset/base.py
+++ b/mongoengine/queryset/base.py
@@ -694,8 +694,8 @@ class BaseQuerySet(object):
     def in_bulk(self, object_ids):
         """Retrieve a set of documents by their ids.
 
-        :param object_ids: a list or tuple of ``ObjectId``\ s
-        :rtype: dict of ObjectIds as keys and collection-specific
+        :param object_ids: a list or tuple of ObjectId's
+        :rtype: dict of ObjectId's as keys and collection-specific
                 Document subclasses as values.
 
         .. versionadded:: 0.3
@@ -1140,7 +1140,7 @@ class BaseQuerySet(object):
 
     def explain(self):
         """Return an explain plan record for the
-        :class:`~mongoengine.queryset.QuerySet`\ 's cursor.
+        :class:`~mongoengine.queryset.QuerySet` cursor.
         """
         return self._cursor.explain()
 
diff --git a/tests/fields/test_complex_datetime_field.py b/tests/fields/test_complex_datetime_field.py
index f0a6b96e..5bd6c56b 100644
--- a/tests/fields/test_complex_datetime_field.py
+++ b/tests/fields/test_complex_datetime_field.py
@@ -65,7 +65,7 @@ class ComplexDateTimeFieldTest(MongoDBTestCase):
         for values in itertools.product([2014], mm, dd, hh, ii, ss, microsecond):
             stored = LogEntry(date=datetime.datetime(*values)).to_mongo()["date"]
             assert (
-                re.match("^\d{4},\d{2},\d{2},\d{2},\d{2},\d{2},\d{6}$", stored)
+                re.match(r"^\d{4},\d{2},\d{2},\d{2},\d{2},\d{2},\d{6}$", stored)
                 is not None
             )
 
@@ -74,7 +74,7 @@ class ComplexDateTimeFieldTest(MongoDBTestCase):
             "date_with_dots"
         ]
         assert (
-            re.match("^\d{4}.\d{2}.\d{2}.\d{2}.\d{2}.\d{2}.\d{6}$", stored) is not None
+            re.match(r"^\d{4}.\d{2}.\d{2}.\d{2}.\d{2}.\d{2}.\d{6}$", stored) is not None
         )
 
     def test_complexdatetime_usage(self):

From c0c0efce188b32f4e59da89ead845a17b824b236 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastien=20G=C3=A9rard?= <bastien.gerard@cluepoints.com>
Date: Sun, 15 Mar 2020 22:14:26 +0100
Subject: [PATCH 09/11] improve docstring related to #2267 and document the
 change in the changelog

---
 docs/changelog.rst           | 1 +
 mongoengine/queryset/base.py | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 8dcea62a..41ff8c85 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -8,6 +8,7 @@ Development
 - (Fill this out as you fix issues and develop your features).
 - Add Mongo 4.0 to Travis
 - 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
 
 Changes in 0.19.1
 =================
diff --git a/mongoengine/queryset/base.py b/mongoengine/queryset/base.py
index 9671a3dc..fbf0a1ba 100644
--- a/mongoengine/queryset/base.py
+++ b/mongoengine/queryset/base.py
@@ -1026,9 +1026,11 @@ class BaseQuerySet(object):
 
             posts = BlogPost.objects(...).fields(comments=0)
 
-        To retrieve a subrange of array elements:
+        To retrieve a subrange or sublist of array elements,
+        support exist for both the `slice` and `elemMatch` projection operator:
 
             posts = BlogPost.objects(...).fields(slice__comments=5)
+            posts = BlogPost.objects(...).fields(elemMatch__comments="test")
 
         :param kwargs: A set of keyword arguments identifying what to
             include, exclude, or slice.

From ad0669a32605bb7d9984b1830349d82c208b3c94 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastien=20G=C3=A9rard?= <bastien.gerard@cluepoints.com>
Date: Mon, 16 Mar 2020 22:39:31 +0100
Subject: [PATCH 10/11] update changelog

---
 docs/changelog.rst | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 7f68bbe5..1bfb190d 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -8,13 +8,9 @@ Development
 - (Fill this out as you fix issues and develop your features).
 - Add Mongo 4.0 to Travis
 - 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
-
-Changes in 0.19.2
-=================
+- 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
 
-
 Changes in 0.19.1
 =================
 - Requires Pillow < 7.0.0 as it dropped Python2 support

From aadc6262edc5627bafbef41a7c814fedbe66fdb2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bastien=20G=C3=A9rard?= <bastien.gerard@cluepoints.com>
Date: Tue, 17 Mar 2020 21:10:52 +0100
Subject: [PATCH 11/11] remove qs.slave_okay() that is deprecated since
 pymongo3

---
 docs/changelog.rst           |  1 +
 mongoengine/queryset/base.py | 16 ----------------
 2 files changed, 1 insertion(+), 16 deletions(-)

diff --git a/docs/changelog.rst b/docs/changelog.rst
index 1bfb190d..b2090645 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -10,6 +10,7 @@ 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
+- Remove method queryset.slave_okay() that was deprecated a while ago and disappeared since pymongo3
 
 Changes in 0.19.1
 =================
diff --git a/mongoengine/queryset/base.py b/mongoengine/queryset/base.py
index fbf0a1ba..95606f2a 100644
--- a/mongoengine/queryset/base.py
+++ b/mongoengine/queryset/base.py
@@ -60,7 +60,6 @@ class BaseQuerySet(object):
         self._ordering = None
         self._snapshot = False
         self._timeout = True
-        self._slave_okay = False
         self._read_preference = None
         self._iter = False
         self._scalar = []
@@ -775,7 +774,6 @@ class BaseQuerySet(object):
             "_ordering",
             "_snapshot",
             "_timeout",
-            "_slave_okay",
             "_read_preference",
             "_iter",
             "_scalar",
@@ -1172,20 +1170,6 @@ class BaseQuerySet(object):
         queryset._timeout = enabled
         return queryset
 
-    # DEPRECATED. Has no more impact on PyMongo 3+
-    def slave_okay(self, enabled):
-        """Enable or disable the slave_okay when querying.
-
-        :param enabled: whether or not the slave_okay is enabled
-
-        .. deprecated:: Ignored with PyMongo 3+
-        """
-        msg = "slave_okay is deprecated as it has no impact when using PyMongo 3+."
-        warnings.warn(msg, DeprecationWarning)
-        queryset = self.clone()
-        queryset._slave_okay = enabled
-        return queryset
-
     def read_preference(self, read_preference):
         """Change the read_preference when querying.