[1.11.x] Fixed #28230 -- Allowed DjangoJsonEncoder to serialize CallableBool.

django/core/serializers/json.py

@@ -16,6 +16,7 @@ from django.core.serializers.python import (
     Deserializer as PythonDeserializer, Serializer as PythonSerializer,
 )
 from django.utils import six
+from django.utils.deprecation import CallableBool
 from django.utils.duration import duration_iso_string
 from django.utils.functional import Promise
 from django.utils.timezone import is_aware
@@ -117,5 +118,7 @@ class DjangoJSONEncoder(json.JSONEncoder):
             return str(o)
         elif isinstance(o, Promise):
             return six.text_type(o)
+        elif isinstance(o, CallableBool):
+            return bool(o)
         else:
             return super(DjangoJSONEncoder, self).default(o)

docs/releases/1.11.2.txt

@@ -29,3 +29,6 @@ Bugfixes
 * Fixed a regression where ``Model._state.adding`` wasn't set correctly on
   multi-table inheritance parent models after saving a child model
   (:ticket:`28210`).
+
+* Allowed ``DjangoJSONEncoder`` to serialize
+  ``django.utils.deprecation.CallableBool`` (:ticket:`28230`).

tests/serializers/test_json.py

@@ -12,6 +12,7 @@ from django.core.serializers.json import DjangoJSONEncoder
 from django.db import models
 from django.test import SimpleTestCase, TestCase, TransactionTestCase
 from django.test.utils import isolate_apps
+from django.utils.deprecation import CallableFalse, CallableTrue
 from django.utils.translation import override, ugettext_lazy
 
 from .models import Score
@@ -315,3 +316,7 @@ class DjangoJSONEncoderTests(SimpleTestCase):
             json.dumps({'duration': duration}, cls=DjangoJSONEncoder),
             '{"duration": "P0DT00H00M00S"}'
         )
+
+    def test_callable_bool(self):
+        self.assertEqual(json.dumps(CallableTrue, cls=DjangoJSONEncoder), 'true')
+        self.assertEqual(json.dumps(CallableFalse, cls=DjangoJSONEncoder), 'false')