Select proper default for output_field based on distinct value

Author: Javier Palacios

src/django_mysql/models/aggregates.py

@@ -1,4 +1,5 @@
 from django.db.models import Aggregate, CharField
+from django_mysql.models.fields import SetCharField, ListCharField
 
 
 class BitAnd(Aggregate):
@@ -24,8 +25,10 @@ def __init__(
     ):
 
         if "output_field" not in extra:
-            # This can/will be improved to SetTextField or ListTextField
-            extra["output_field"] = CharField()
+            if distinct:
+                extra['output_field'] = SetCharField(CharField())
+            else:
+                extra['output_field'] = ListCharField(CharField())
 
         super().__init__(expression, **extra)