[2.2.x] Fixed #30254 -- Allowed model metaclasses to access the attribute dict in __init__().

Regression in a68ea231012434b522ce45c513d84add516afa60.

Backport of 58ad030d05fa50cfed327368ab61defca3303e02 from master.

1 files changed, 19 insertions, 1 deletions

diff --git a/tests/model_regress/tests.py b/tests/model_regress/tests.py
index e3977ee316..28eed87008 100644
--- a/tests/model_regress/tests.py
+++ b/tests/model_regress/tests.py
@@ -2,9 +2,10 @@ import datetime
 from operator import attrgetter
 
 from django.core.exceptions import ValidationError
-from django.db import router
+from django.db import models, router
 from django.db.models.sql import InsertQuery
 from django.test import TestCase, skipUnlessDBFeature
+from django.test.utils import isolate_apps
 from django.utils.timezone import get_fixed_timezone
 
 from .models import (
@@ -217,6 +218,23 @@ class ModelTests(TestCase):
         m3 = Model3.objects.get(model2=1000)
         m3.model2
 
+    @isolate_apps('model_regress')
+    def test_metaclass_can_access_attribute_dict(self):
+        """
+        Model metaclasses have access to the class attribute dict in
+        __init__() (#30254).
+        """
+        class HorseBase(models.base.ModelBase):
+            def __init__(cls, name, bases, attrs):
+                super(HorseBase, cls).__init__(name, bases, attrs)
+                cls.horns = (1 if 'magic' in attrs else 0)
+
+        class Horse(models.Model, metaclass=HorseBase):
+            name = models.CharField(max_length=255)
+            magic = True
+
+        self.assertEqual(Horse.horns, 1)
+
 
 class ModelValidationTest(TestCase):
     def test_pk_validation(self):