Fix the aggregates using the wrong side of the join when doing a self…

…-referential aggregate. (#333)

CHANGELOG.rst

@@ -2,6 +2,10 @@
 
 Changelog
 =========
+0.15.22
+-------
+* Fix the aggregates using the wrong side of the join when doing a self-referential aggregation.
+
 0.15.21
 -------
 * Fixed invalid ``var IN ()`` SQL generated using ``__in=`` and ``__not_in`` filters.

tests/test_relations.py

@@ -213,11 +213,14 @@ async def test_self_ref_filter_both(self):
     async def test_self_ref_annotate(self):
         self.maxDiff = None
         root = await Employee.create(name="Root")
+        await Employee.create(name="Loose")
         await Employee.create(name="1. First H1", manager=root)
         await Employee.create(name="2. Second H1", manager=root)
 
         root_ann = await Employee.get(name="Root").annotate(num_team_members=Count("team_members"))
         self.assertEqual(root_ann.num_team_members, 2)
+        root_ann = await Employee.get(name="Loose").annotate(num_team_members=Count("team_members"))
+        self.assertEqual(root_ann.num_team_members, 0)
 
     async def test_prefetch_related_fk(self):
         tournament = await Tournament.create(name="New Tournament")

tortoise/functions.py

@@ -5,7 +5,7 @@
 from pypika.terms import Function as BaseFunction
 
 from tortoise.exceptions import ConfigurationError
-from tortoise.fields.relational import ForeignKeyFieldInstance, RelationalField
+from tortoise.fields.relational import BackwardFKRelation, ForeignKeyFieldInstance, RelationalField
 
 if TYPE_CHECKING:  # pragma: nocoverage
     from tortoise.models import Model
@@ -54,9 +54,15 @@ def _resolve_field_for_model(
             if field_split[0] in model._meta.fetch_fields:
                 related_field = cast(RelationalField, model._meta.fields_map[field_split[0]])
                 related_field_meta = related_field.model_class._meta
+                related_table = related_field_meta.basetable
+                if isinstance(related_field, BackwardFKRelation):
+                    if table == related_table:
+                        related_table = related_table.as_(
+                            f"{table.get_table_name()}__{field_split[0]}"
+                        )
                 join = (table, field_split[0], related_field)
                 function_joins.append(join)
-                field = related_field_meta.basetable[related_field_meta.db_pk_field]
+                field = related_table[related_field_meta.db_pk_field]
             else:
                 field_object = model._meta.fields_map[field_split[0]]
                 if field_object.source_field: