Refs #28748 -- Reallowed lazy model field choices.

Regression in 3aa9ab39cc.

django/db/models/fields/__init__.py

@@ -244,10 +244,10 @@ class Field(RegisterLookupMixin):
         if not self.choices:
             return []
 
-        def is_value(value):
+        def is_value(value, accept_promise=True):
-            return isinstance(value, (str, Promise)) or not is_iterable(value)
+            return isinstance(value, (str, Promise) if accept_promise else str) or not is_iterable(value)
 
-        if is_value(self.choices):
+        if is_value(self.choices, accept_promise=False):
             return [
                 checks.Error(
                     "'choices' must be an iterable (e.g., a list or tuple).",

tests/invalid_models_tests/test_ordinary_fields.py

@@ -4,6 +4,7 @@ from django.core.checks import Error, Warning as DjangoWarning
 from django.db import connection, models
 from django.test import SimpleTestCase, TestCase, skipIfDBFeature
 from django.test.utils import isolate_apps, override_settings
+from django.utils.functional import lazy
 from django.utils.timezone import now
 from django.utils.translation import gettext_lazy as _
 
@@ -188,6 +189,12 @@ class CharFieldTests(TestCase):
 
         self.assertEqual(Model._meta.get_field('field').check(), [])
 
+    def test_lazy_choices(self):
+        class Model(models.Model):
+            field = models.CharField(max_length=10, choices=lazy(lambda: [[1, '1'], [2, '2']], tuple)())
+
+        self.assertEqual(Model._meta.get_field('field').check(), [])
+
     def test_choices_named_group(self):
         class Model(models.Model):
             field = models.CharField(