add contained_by lookup

django_mongodb/fields/array.py

@@ -248,6 +248,16 @@ def as_mql(self, compiler, connection):
         return {"$and": [{"$ne": [lhs_mql, None]}, {"$setIsSubset": [value, lhs_mql]}]}
 
 
+@ArrayField.register_lookup
+class ArrayContainedBy(ArrayRHSMixin, FieldGetDbPrepValueMixin, Lookup):
+    lookup_name = "contained_by"
+
+    def as_mql(self, compiler, connection):
+        lhs_mql = process_lhs(self, compiler, connection)
+        value = process_rhs(self, compiler, connection)
+        return {"$and": [{"$ne": [lhs_mql, None]}, {"$setIsSubset": [lhs_mql, value]}]}
+
+
 @ArrayField.register_lookup
 class ArrayExact(ArrayRHSMixin, Exact):
     pass

docs/source/fields.rst

@@ -106,6 +106,25 @@ data. It uses the ``$setIntersection`` operator. For example:
     >>> Post.objects.filter(tags__contains=["django", "thoughts"])
     <QuerySet [<Post: First post>]>
 
+``contained_by``
+~~~~~~~~~~~~~~~~
+
+This is the inverse of the :lookup:`contains <arrayfield.contains>` lookup -
+the objects returned will be those where the data is a subset of the values
+passed. It uses the ``$setIntersection`` operator. For example:
+
+.. code-block:: pycon
+
+    >>> Post.objects.create(name="First post", tags=["thoughts", "django"])
+    >>> Post.objects.create(name="Second post", tags=["thoughts"])
+    >>> Post.objects.create(name="Third post", tags=["tutorial", "django"])
+
+    >>> Post.objects.filter(tags__contained_by=["thoughts", "django"])
+    <QuerySet [<Post: First post>, <Post: Second post>]>
+
+    >>> Post.objects.filter(tags__contained_by=["thoughts", "django", "tutorial"])
+    <QuerySet [<Post: First post>, <Post: Second post>, <Post: Third post>]>
+
 .. fieldlookup:: arrayfield.overlap
 
 ``overlap``

tests/model_fields_/test_arrayfield.py

@@ -336,6 +336,18 @@ def test_in_as_F_object(self):
             self.objs,
         )
 
+    def test_contained_by(self):
+        self.assertSequenceEqual(
+            NullableIntegerArrayModel.objects.filter(field__contained_by=[1, 2]),
+            self.objs[:2],
+        )
+
+    def test_contained_by_including_F_object(self):
+        self.assertSequenceEqual(
+            NullableIntegerArrayModel.objects.filter(field__contained_by=[models.F("order"), 2]),
+            self.objs[:3],
+        )
+
     def test_contains(self):
         self.assertSequenceEqual(
             NullableIntegerArrayModel.objects.filter(field__contains=[2]),
@@ -370,6 +382,9 @@ def test_icontains(self):
     def test_contains_charfield(self):
         self.assertSequenceEqual(CharArrayModel.objects.filter(field__contains=["text"]), [])
 
+    def test_contained_by_charfield(self):
+        self.assertSequenceEqual(CharArrayModel.objects.filter(field__contained_by=["text"]), [])
+
     def test_overlap_charfield(self):
         self.assertSequenceEqual(CharArrayModel.objects.filter(field__overlap=["text"]), [])