Remove values list alias

docs/changelog.rst

@@ -35,6 +35,7 @@ Changes in 1.0.0
   ``(changed_fields, unset_fields)`` tuple containing two disjoint lists of
   database paths. ``_clear_changed_fields()`` was renamed to
   ``_clear_updated_fields()``.
+- BREAKING CHANGE: Remove ``QuerySet.values_list()`` as it was just an alias to scalar. Use ``QuerySet.scalar()`` instead. #2931
 - Add a warning that ``mongoengine.org`` is no longer controlled by the MongoEngine
   project and appears to be an expired domain takeover.
 - Bug Fix - Fix querying GenericReferenceField with __in operator #2886
@@ -66,6 +67,7 @@ Changes in 1.0.0
 - Improve error message in case a document assigned to a ReferenceField wasn't saved yet #1955
 - BugFix - Fix inc/dec atomic updates rejecting deltas outside a field's min_value/max_value #2339
 - BugFix - Take `where()` into account when using `.modify()`, as in MyDocument.objects().where("this[field] >= this[otherfield]").modify(field='new') #2044
+- BugFix: null embedded scalar values raises AttributeError #2896
 
 Changes in 0.29.3
 =================

mongoengine/queryset/base.py

@@ -1296,10 +1296,6 @@ def scalar(self, *fields):
 
         return queryset
 
-    def values_list(self, *fields):
-        """An alias for scalar"""
-        return self.scalar(*fields)
-
     def as_pymongo(self):
         """Instead of returning Document instances, return raw values from
         pymongo.
@@ -2023,6 +2019,8 @@ def lookup(obj, name):
             chunks = name.split("__")
             for chunk in chunks:
                 obj = getattr(obj, chunk)
+                if obj is None:
+                    break
             return obj
 
         data = [lookup(doc, n) for n in self._scalar]

tests/queryset/test_queryset.py

@@ -21,6 +21,7 @@
 from mongoengine.queryset import (
     DoesNotExist,
     MultipleObjectsReturned,
+    Q,
     QuerySet,
     QuerySetManager,
     queryset_manager,
@@ -4724,6 +4725,35 @@ class Person(Document):
             ("Gabriel Falcao", 23, "New York"),
         ]
 
+    def test_scalar_embedded_null_parents(self):
+        """Test a multi-scalar query on embedded fields raises an exception when the parent field is null."""
+
+        class EmbeddedModelA(EmbeddedDocument):
+            designator = StringField()
+
+        class Container(Document):
+            source = EmbeddedDocumentField(EmbeddedModelA)
+            target = EmbeddedDocumentField(EmbeddedModelA, null=True)
+
+        # Create one with both values
+        Container(
+            source=EmbeddedModelA(designator="value1"),
+            target=EmbeddedModelA(designator="value2"),
+        ).save()
+
+        # Create one with a null target, but the source value will match the query
+        Container(
+            source=EmbeddedModelA(designator="value1"),
+            target=None,
+        ).save()
+
+        queryset = Container.objects.filter(
+            Q(source__designator="value1") | Q(target__designator="value2")
+        ).scalar("source__designator", "target__designator")
+        # This should not raise an AttributeError on NoneType for the second Container's target__designator
+        values = list(queryset)
+        assert values == [("value1", "value2"), ("value1", None)]
+
     def test_scalar_decimal(self):
         from decimal import Decimal