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 7941e970..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. @@ -1037,7 +1039,7 @@ 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..f6d1a916 100644 --- a/tests/queryset/test_queryset.py +++ b/tests/queryset/test_queryset.py @@ -4476,6 +4476,74 @@ 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()