Fixed bug in checking the existence of custom __init__ method in an o…

polymorphic/query.py

@@ -73,7 +73,7 @@ def transmogrify(cls, obj):
     """
     Upcast a class to a different type without asking questions.
     """
-    if "__init__" not in obj.__dict__:
+    if "__init__" not in obj.__class__.__dict__:
         # Just assign __class__ to a different value.
         new = obj
         new.__class__ = cls

polymorphic/tests/migrations/0002_blueheadduck_delete_inlinemodelbase_and_more.py

@@ -0,0 +1,36 @@
+# Generated by Django 4.2.15 on 2024-08-20 06:34
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('tests', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='BlueHeadDuck',
+            fields=[
+                ('duck_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='tests.duck')),
+            ],
+            options={
+                'abstract': False,
+                'base_manager_name': 'objects',
+            },
+            bases=('tests.duck',),
+        ),
+        migrations.CreateModel(
+            name='PurpleHeadDuck',
+            fields=[
+            ],
+            options={
+                'proxy': True,
+                'indexes': [],
+                'constraints': [],
+            },
+            bases=('tests.blueheadduck',),
+        ),
+    ]

polymorphic/tests/models.py

@@ -496,3 +496,26 @@ class SubclassSelectorProxyConcreteModel(SubclassSelectorProxyModel):
 
 class NonPolymorphicParent(PolymorphicModel, Group):
     test = models.CharField(max_length=22, default="test_non_polymorphic_parent")
+
+
+# models for https://github.com/jazzband/django-polymorphic/issues/615
+
+
+class BlueHeadDuck(Duck):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.color = "blue"
+
+
+class HomeDuck(models.Model):
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.home = "Duckburg"
+
+    class Meta:
+        abstract = True
+
+
+class PurpleHeadDuck(HomeDuck, BlueHeadDuck):
+    class Meta:
+        proxy = True

polymorphic/tests/test_query.py

@@ -0,0 +1,12 @@
+from polymorphic.tests.models import Duck, PurpleHeadDuck
+
+
+def test_transmogrify_with_init(db):
+    pur = PurpleHeadDuck.objects.create()
+    assert pur.color == "blue"
+    assert pur.home == "Duckburg"
+
+    pur = Duck.objects.get(id=pur.id)
+    assert pur.color == "blue"
+    # issues/615 fixes following line:
+    assert pur.home == "Duckburg"