From 21420096c4db78ccb8f549a29d662cff870d363c Mon Sep 17 00:00:00 2001
From: orlnub123 <30984274+orlnub123@users.noreply.github.com>
Date: Thu, 22 Mar 2018 16:05:31 +0300
Subject: [PATCH] Fixed #29247 -- Allowed blank model field choice to be
 defined in nested choices.

---
 django/db/models/fields/__init__.py |  3 +--
 tests/model_fields/tests.py         | 13 +++++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index 44052a7bc36..f21a6df7f79 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -816,8 +816,7 @@ class Field(RegisterLookupMixin):
         if self.choices:
             choices = list(self.choices)
             if include_blank:
-                named_groups = isinstance(choices[0][1], (list, tuple))
-                blank_defined = not named_groups and any(choice in ('', None) for choice, __ in choices)
+                blank_defined = any(choice in ('', None) for choice, _ in self.flatchoices)
                 if not blank_defined:
                     choices = blank_choice + choices
             return choices
diff --git a/tests/model_fields/tests.py b/tests/model_fields/tests.py
index fb0098a262c..45f61a00346 100644
--- a/tests/model_fields/tests.py
+++ b/tests/model_fields/tests.py
@@ -140,6 +140,19 @@ class GetChoicesTests(SimpleTestCase):
         f = models.CharField(choices=choices)
         self.assertEqual(f.get_choices(include_blank=True), choices)
 
+    def test_blank_in_grouped_choices(self):
+        choices = [
+            ('f', 'Foo'),
+            ('b', 'Bar'),
+            ('Group', (
+                ('', 'No Preference'),
+                ('fg', 'Foo'),
+                ('bg', 'Bar'),
+            )),
+        ]
+        f = models.CharField(choices=choices)
+        self.assertEqual(f.get_choices(include_blank=True), choices)
+
     def test_lazy_strings_not_evaluated(self):
         lazy_func = lazy(lambda x: 0 / 0, int)  # raises ZeroDivisionError if evaluated.
         f = models.CharField(choices=[(lazy_func('group'), (('a', 'A'), ('b', 'B')))])