Fixed #23455 -- Accept either bytes or text for related_name, convert to text.

django/db/models/fields/related.py

@@ -14,7 +14,7 @@ from django.db.models.lookups import IsNull
 from django.db.models.related import RelatedObject, PathInfo
 from django.db.models.query import QuerySet
 from django.db.models.expressions import Col
-from django.utils.encoding import smart_text
+from django.utils.encoding import force_text, smart_text
 from django.utils import six
 from django.utils.translation import ugettext_lazy as _
 from django.utils.functional import curry, cached_property
@@ -280,7 +280,7 @@ class RelatedField(Field):
             sup.contribute_to_class(cls, name, virtual_only=virtual_only)
 
         if not cls._meta.abstract and self.rel.related_name:
-            related_name = self.rel.related_name % {
+            related_name = force_text(self.rel.related_name) % {
                 'class': cls.__name__.lower(),
                 'app_label': cls._meta.app_label.lower()
             }

docs/releases/1.7.2.txt

@@ -125,6 +125,6 @@ Bugfixes
 * Fixed a crash in the admin when using "Save as new" and also deleting a
   related inline (:ticket:`23857`).
 
-* Removed auto-conversion of ``related_name`` to unicode in field
-  deconstruction, to maintain consistency of bytes/text in migrations matching
-  the original values (:ticket:`23455` and :ticket:`23982`).
+* Always converted ``related_name`` to text (unicode), since that is required
+  on Python 3 for interpolation. Removed conversion of ``related_name`` to text
+  in migration deconstruction (:ticket:`23455` and :ticket:`23982`).

tests/model_fields/models.py

@@ -25,7 +25,7 @@ def get_foo():
 
 class Bar(models.Model):
     b = models.CharField(max_length=10)
-    a = models.ForeignKey(Foo, default=get_foo)
+    a = models.ForeignKey(Foo, default=get_foo, related_name=b'bars')
 
 
 class Whiz(models.Model):

tests/model_fields/tests.py

@@ -199,6 +199,10 @@ class ForeignKeyTests(test.TestCase):
         warnings = checks.run_checks()
         self.assertEqual(warnings, expected_warnings)
 
+    def test_related_name_converted_to_text(self):
+        rel_name = Bar._meta.get_field_by_name('a')[0].rel.related_name
+        self.assertIsInstance(rel_name, six.text_type)
+
 
 class DateTimeFieldTests(unittest.TestCase):
     def test_datetimefield_to_python_usecs(self):