rebuild the registry of relationships

tests/test_same_table_joins.py

@@ -0,0 +1,77 @@
+import databases
+import pytest
+import sqlalchemy
+
+import orm
+from tests.settings import DATABASE_URL
+
+database = databases.Database(DATABASE_URL, force_rollback=True)
+metadata = sqlalchemy.MetaData()
+
+
+class SchoolClass(orm.Model):
+    __tablename__ = "schoolclasses"
+    __metadata__ = metadata
+    __database__ = database
+
+    id = orm.Integer(primary_key=True)
+    name = orm.String(length=100)
+
+
+class Category(orm.Model):
+    __tablename__ = "cateogories"
+    __metadata__ = metadata
+    __database__ = database
+
+    id = orm.Integer(primary_key=True)
+    name = orm.String(length=100)
+
+
+class Student(orm.Model):
+    __tablename__ = "students"
+    __metadata__ = metadata
+    __database__ = database
+
+    id = orm.Integer(primary_key=True)
+    name = orm.String(length=100)
+    schoolclass = orm.ForeignKey(SchoolClass)
+    category = orm.ForeignKey(Category, nullable=True)
+
+
+class Teacher(orm.Model):
+    __tablename__ = "teachers"
+    __metadata__ = metadata
+    __database__ = database
+
+    id = orm.Integer(primary_key=True)
+    name = orm.String(length=100)
+    schoolclass = orm.ForeignKey(SchoolClass)
+    category = orm.ForeignKey(Category, nullable=True)
+
+
+@pytest.fixture(autouse=True, scope="module")
+def create_test_database():
+    engine = sqlalchemy.create_engine(DATABASE_URL)
+    metadata.create_all(engine)
+    yield
+    metadata.drop_all(engine)
+
+
+@pytest.mark.asyncio
+async def test_model_multiple_instances_of_same_table_in_schema():
+    async with database:
+        class1 = await SchoolClass.objects.create(name="Math")
+        category = await Category.objects.create(name="Foreign")
+        category2 = await Category.objects.create(name="Domestic")
+        await Student.objects.create(name="Jane", category=category, schoolclass=class1)
+        await Teacher.objects.create(name="Joe", category=category2, schoolclass=class1)
+
+        classes = await SchoolClass.objects.select_related(['teachers', 'students']).all()
+        assert classes[0].name == 'Math'
+        assert classes[0].students[0].name == 'Jane'
+
+        # related fields of main model are only populated by pk
+        # but you can load them anytime
+        assert classes[0].students[0].schoolclass.name is None
+        await classes[0].students[0].schoolclass.load()
+        assert classes[0].students[0].schoolclass.name == 'Math'