fix merging lists of deeply nested reverse relations

tests/test_queries/test_nested_reverse_relations.py

@@ -0,0 +1,117 @@
+from typing import Optional
+
+import databases
+import pytest
+import sqlalchemy
+
+import ormar
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL)
+metadata = sqlalchemy.MetaData()
+
+
+class BaseMeta(ormar.ModelMeta):
+    metadata = metadata
+    database = database
+
+
+class DataSource(ormar.Model):
+    class Meta(BaseMeta):
+        tablename = "datasources"
+
+    source_id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=200, unique=True, index=True)
+
+
+class DataSourceTable(ormar.Model):
+    class Meta(BaseMeta):
+        tablename = "datasource_tables"
+
+    datasource_table_id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=200, index=True)
+    data_source: Optional[DataSource] = ormar.ForeignKey(
+        DataSource,
+        name="data_source_id",
+        related_name="datasource_tables",
+        ondelete="CASCADE",
+    )
+
+
+class DataSourceTableColumn(ormar.Model):
+    class Meta(BaseMeta):
+        tablename = "datasource_table_columns"
+
+    datasource_table_column_id: int = ormar.Integer(primary_key=True)
+    name: str = ormar.String(max_length=200, index=True)
+    data_type: str = ormar.String(max_length=200)
+    datasource_table: Optional[DataSourceTable] = ormar.ForeignKey(
+        DataSourceTable,
+        name="datasource_table_id",
+        related_name="datasource_table_columns",
+        ondelete="CASCADE",
+    )
+
+
+@pytest.fixture(autouse=True, scope="module")
+def create_test_database():
+    engine = sqlalchemy.create_engine(DATABASE_URL)
+    metadata.drop_all(engine)
+    metadata.create_all(engine)
+    yield
+    metadata.drop_all(engine)
+
+
+@pytest.mark.asyncio
+async def test_double_nested_reverse_relation():
+    async with database:
+        data_source = await DataSource(name="local").save()
+        test_tables = [
+            {
+                "name": "test1",
+                "datasource_table_columns": [
+                    {"name": "col1", "data_type": "test"},
+                    {"name": "col2", "data_type": "test2"},
+                    {"name": "col3", "data_type": "test3"},
+                ],
+            },
+            {
+                "name": "test2",
+                "datasource_table_columns": [
+                    {"name": "col4", "data_type": "test"},
+                    {"name": "col5", "data_type": "test2"},
+                    {"name": "col6", "data_type": "test3"},
+                ],
+            },
+        ]
+        data_source.datasource_tables = test_tables
+        await data_source.save_related(save_all=True, follow=True)
+
+        tables = await DataSourceTable.objects.all()
+        assert len(tables) == 2
+
+        columns = await DataSourceTableColumn.objects.all()
+        assert len(columns) == 6
+
+        data_source = (
+            await DataSource.objects.select_related(
+                "datasource_tables__datasource_table_columns"
+            )
+            .filter(datasource_tables__name__in=["test1", "test2"], name="local")
+            .get()
+        )
+        assert len(data_source.datasource_tables) == 2
+        assert len(data_source.datasource_tables[0].datasource_table_columns) == 3
+        assert (
+            data_source.datasource_tables[0].datasource_table_columns[0].name == "col1"
+        )
+        assert (
+            data_source.datasource_tables[0].datasource_table_columns[2].name == "col3"
+        )
+        assert len(data_source.datasource_tables[1].datasource_table_columns) == 3
+        assert (
+            data_source.datasource_tables[1].datasource_table_columns[0].name == "col4"
+        )
+        assert (
+            data_source.datasource_tables[1].datasource_table_columns[2].name == "col6"
+        )