From 8f288fe45875050ac39985dcf9bcc304b6c1f15e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bastien=20G=C3=A9rard?= Date: Sun, 29 Sep 2019 22:48:46 +0200 Subject: [PATCH 01/13] add mongodb 4.0 to travis and docs --- .travis.yml | 10 ++++++---- README.rst | 4 ++-- 2 files changed, 8 insertions(+), 6 deletions(-) diff --git a/.travis.yml b/.travis.yml index 54a6befd..21321841 100644 --- a/.travis.yml +++ b/.travis.yml @@ -3,7 +3,7 @@ # with a very large number of jobs, hence we only test a subset of all the # combinations: # * MongoDB v3.4 & the latest PyMongo v3.x is currently the "main" setup, -# tested against Python v2.7, v3.5, v3.6, and PyPy. +# tested against Python v2.7, v3.5, v3.6, v3.7, PyPy and PyPy3. # * Besides that, we test the lowest actively supported Python/MongoDB/PyMongo # combination: MongoDB v3.4, PyMongo v3.4, Python v2.7. # * MongoDB v3.6 is tested against Python v3.6, and PyMongo v3.6, v3.7, v3.8. @@ -30,15 +30,16 @@ dist: xenial env: global: + - MONGODB_4_0=4.0.12 - MONGODB_3_4=3.4.17 - MONGODB_3_6=3.6.12 + - PYMONGO_3_9=3.9 - PYMONGO_3_6=3.6 - PYMONGO_3_4=3.4 matrix: - - MONGODB=${MONGODB_3_4} PYMONGO=${PYMONGO_3_6} + - MONGODB=${MONGODB_3_4} PYMONGO=${PYMONGO_3_9} matrix: - # Finish the build as soon as one job fails fast_finish: true @@ -47,7 +48,8 @@ matrix: env: MONGODB=${MONGODB_3_4} PYMONGO=${PYMONGO_3_4} - python: 3.7 env: MONGODB=${MONGODB_3_6} PYMONGO=${PYMONGO_3_6} - + - python: 3.7 + env: MONGODB=${MONGODB_4_0} PYMONGO=${PYMONGO_3_9} install: # Install Mongo diff --git a/README.rst b/README.rst index 679980f8..82b32893 100644 --- a/README.rst +++ b/README.rst @@ -26,10 +26,10 @@ an `API reference `_. Supported MongoDB Versions ========================== -MongoEngine is currently tested against MongoDB v3.4 and v3.6. Future versions +MongoEngine is currently tested against MongoDB v3.4, v3.6 and v4.0. Future versions should be supported as well, but aren't actively tested at the moment. Make sure to open an issue or submit a pull request if you experience any problems -with MongoDB version > 3.6. +with MongoDB version > 4.0. Installation ============ From b61c8cd104975b5fb47681387abc443c8c8430b2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bastien=20G=C3=A9rard?= Date: Tue, 1 Oct 2019 22:17:19 +0200 Subject: [PATCH 02/13] fix tox envs --- tox.ini | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tox.ini b/tox.ini index a1ae8444..a7921c61 100644 --- a/tox.ini +++ b/tox.ini @@ -1,5 +1,5 @@ [tox] -envlist = {py27,py35,pypy,pypy3}-{mg34,mg36} +envlist = {py27,py35,pypy,pypy3}-{mg34,mg36, mg39} [testenv] commands = @@ -8,5 +8,6 @@ deps = nose mg34: pymongo>=3.4,<3.5 mg36: pymongo>=3.6,<3.7 + mg39: pymongo>=3.9,<4.0 setenv = PYTHON_EGG_CACHE = {envdir}/python-eggs From 18b68f1b8034457384daa5bdbd7d780055e21690 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bastien=20G=C3=A9rard?= Date: Sun, 12 Jan 2020 21:29:18 +0100 Subject: [PATCH 03/13] update travis mongo 4.0 to latest 4.0.13 --- .travis.yml | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/.travis.yml b/.travis.yml index f7880649..a7d6da1a 100644 --- a/.travis.yml +++ b/.travis.yml @@ -31,7 +31,7 @@ dist: xenial env: global: - - MONGODB_4_0=4.0.12 + - MONGODB_4_0=4.0.13 - MONGODB_3_4=3.4.17 - MONGODB_3_6=3.6.12 - PYMONGO_3_10=3.10 From e0565ddac5cd62f9fd05c69187b49a20bb644035 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bastien=20G=C3=A9rard?= Date: Sun, 12 Jan 2020 21:31:28 +0100 Subject: [PATCH 04/13] update changelog --- docs/changelog.rst | 1 + 1 file changed, 1 insertion(+) diff --git a/docs/changelog.rst b/docs/changelog.rst index b8e6ae56..d924a2c1 100644 --- a/docs/changelog.rst +++ b/docs/changelog.rst @@ -6,6 +6,7 @@ Changelog Development =========== - (Fill this out as you fix issues and develop your features). +- Add Mongo 4.0 to Travis Changes in 0.19.1 ================= From 605de59bd08d9d4f54f695c7f73a1458975d479f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bastien=20G=C3=A9rard?= Date: Sun, 12 Jan 2020 21:37:32 +0100 Subject: [PATCH 05/13] improve travis + fix tox mg310 --- .travis.yml | 9 +++++---- tox.ini | 2 +- 2 files changed, 6 insertions(+), 5 deletions(-) diff --git a/.travis.yml b/.travis.yml index a7d6da1a..62bbacb1 100644 --- a/.travis.yml +++ b/.travis.yml @@ -31,13 +31,14 @@ dist: xenial env: global: - - MONGODB_4_0=4.0.13 - MONGODB_3_4=3.4.17 - MONGODB_3_6=3.6.12 - - PYMONGO_3_10=3.10 - - PYMONGO_3_9=3.9 - - PYMONGO_3_6=3.6 + - MONGODB_4_0=4.0.13 + - PYMONGO_3_4=3.4 + - PYMONGO_3_6=3.6 + - PYMONGO_3_9=3.9 + - PYMONGO_3_10=3.10 matrix: - MONGODB=${MONGODB_3_4} PYMONGO=${PYMONGO_3_10} diff --git a/tox.ini b/tox.ini index c3789b7d..396817ca 100644 --- a/tox.ini +++ b/tox.ini @@ -1,5 +1,5 @@ [tox] -envlist = {py27,py35,pypy,pypy3}-{mg34,mg36, mg39} +envlist = {py27,py35,pypy,pypy3}-{mg34,mg36,mg39,mg310} [testenv] commands = From 450658d7ac2b26be7849f8f0599fff06bb7e6ebc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bastien=20G=C3=A9rard?= Date: Tue, 4 Feb 2020 22:51:02 +0100 Subject: [PATCH 06/13] 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 Date: Fri, 14 Feb 2020 16:43:07 -0300 Subject: [PATCH 07/13] 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 Date: Fri, 21 Feb 2020 19:14:34 -0300 Subject: [PATCH 08/13] 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?= Date: Mon, 2 Mar 2020 22:49:21 +0100 Subject: [PATCH 09/13] 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 Date: Tue, 4 Feb 2020 12:35:03 +0100 Subject: [PATCH 10/13] 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 Date: Tue, 4 Feb 2020 12:58:25 +0100 Subject: [PATCH 11/13] 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?= Date: Sun, 15 Mar 2020 21:02:44 +0100 Subject: [PATCH 12/13] 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?= Date: Sun, 15 Mar 2020 22:14:26 +0100 Subject: [PATCH 13/13] 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.