fix per Emanuel

Author: timgraham

django_mongodb/aggregates.py

@@ -1,5 +1,5 @@
 from django.db.models.aggregates import Aggregate, Count, StdDev, Variance
-from django.db.models.expressions import Case, Col, Value, When
+from django.db.models.expressions import Case, Value, When
 from django.db.models.lookups import IsNull
 
 from .query_utils import process_lhs
@@ -16,7 +16,7 @@ def aggregate(
     resolve_inner_expression=False,
     **extra_context,  # noqa: ARG001
 ):
-    if self.filter and not isinstance(self.filter, Col):
+    if self.filter:
         node = self.copy()
         node.filter = None
         source_expressions = node.get_source_expressions()

django_mongodb/compiler.py

@@ -91,7 +91,7 @@ def _prepare_expressions_for_pipeline(self, expression, target, annotation_group
                 rhs = sub_expr.as_mql(self, self.connection, resolve_inner_expression=True)
                 group[alias] = {"$addToSet": rhs}
                 replacing_expr = sub_expr.copy()
-                replacing_expr.set_source_expressions([inner_column])
+                replacing_expr.set_source_expressions([inner_column, None])
             else:
                 group[alias] = sub_expr.as_mql(self, self.connection)
                 replacing_expr = inner_column