From 540ae68a5cc6339c72375fad9b04dc48f3af4c93 Mon Sep 17 00:00:00 2001
From: Claude Paroz <claude@2xlibre.net>
Date: Thu, 9 Mar 2017 15:42:47 +0100
Subject: [PATCH] Fixed #27920 -- Restored empty RadioSelect choice producing
 value=""

Regression in b52c73008a9d67e9ddbb841872dc15cdd3d6ee01.
Thanks Tim Graham for the review.
---
 django/contrib/admin/widgets.py                        | 6 +-----
 django/forms/jinja2/django/forms/widgets/input.html    | 2 +-
 django/forms/templates/django/forms/widgets/input.html | 2 +-
 django/forms/widgets.py                                | 4 ++--
 tests/forms_tests/widget_tests/test_radioselect.py     | 4 +++-
 tests/forms_tests/widget_tests/test_widget.py          | 7 +++++++
 6 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/django/contrib/admin/widgets.py b/django/contrib/admin/widgets.py
index 588bfb58e3..fd57436c46 100644
--- a/django/contrib/admin/widgets.py
+++ b/django/contrib/admin/widgets.py
@@ -347,13 +347,9 @@ class AdminURLFieldWidget(forms.URLInput):
         context = super().get_context(name, value, attrs)
         context['current_label'] = _('Currently:')
         context['change_label'] = _('Change:')
-        context['widget']['href'] = smart_urlquote(context['widget']['value'])
+        context['widget']['href'] = smart_urlquote(context['widget']['value']) if value else ''
         return context
 
-    def format_value(self, value):
-        value = super().format_value(value)
-        return force_text(value)
-
 
 class AdminIntegerFieldWidget(forms.NumberInput):
     class_name = 'vIntegerField'
diff --git a/django/forms/jinja2/django/forms/widgets/input.html b/django/forms/jinja2/django/forms/widgets/input.html
index 7e70d1953f..abbdf6bd26 100644
--- a/django/forms/jinja2/django/forms/widgets/input.html
+++ b/django/forms/jinja2/django/forms/widgets/input.html
@@ -1 +1 @@
-<input type="{{ widget.type }}" name="{{ widget.name }}"{% if widget.value != None and widget.value != "" %} value="{{ widget.value }}"{% endif %}{% include "django/forms/widgets/attrs.html" %} />
+<input type="{{ widget.type }}" name="{{ widget.name }}"{% if widget.value != None %} value="{{ widget.value }}"{% endif %}{% include "django/forms/widgets/attrs.html" %} />
diff --git a/django/forms/templates/django/forms/widgets/input.html b/django/forms/templates/django/forms/widgets/input.html
index 7e70d1953f..abbdf6bd26 100644
--- a/django/forms/templates/django/forms/widgets/input.html
+++ b/django/forms/templates/django/forms/widgets/input.html
@@ -1 +1 @@
-<input type="{{ widget.type }}" name="{{ widget.name }}"{% if widget.value != None and widget.value != "" %} value="{{ widget.value }}"{% endif %}{% include "django/forms/widgets/attrs.html" %} />
+<input type="{{ widget.type }}" name="{{ widget.name }}"{% if widget.value != None %} value="{{ widget.value }}"{% endif %}{% include "django/forms/widgets/attrs.html" %} />
diff --git a/django/forms/widgets.py b/django/forms/widgets.py
index 7db4c69aad..8b1069d040 100644
--- a/django/forms/widgets.py
+++ b/django/forms/widgets.py
@@ -180,8 +180,8 @@ class Widget(metaclass=MediaDefiningClass):
         """
         Return a value as it should appear when rendered in a template.
         """
-        if value is None:
-            value = ''
+        if value == '' or value is None:
+            return None
         if self.is_localized:
             return formats.localize_input(value)
         return force_text(value)
diff --git a/tests/forms_tests/widget_tests/test_radioselect.py b/tests/forms_tests/widget_tests/test_radioselect.py
index fea26cece1..58b2fc408e 100644
--- a/tests/forms_tests/widget_tests/test_radioselect.py
+++ b/tests/forms_tests/widget_tests/test_radioselect.py
@@ -7,8 +7,10 @@ class RadioSelectTest(WidgetTest):
     widget = RadioSelect
 
     def test_render(self):
-        self.check_html(self.widget(choices=self.beatles), 'beatle', 'J', html=(
+        choices = (('', '------'),) + self.beatles
+        self.check_html(self.widget(choices=choices), 'beatle', 'J', html=(
             """<ul>
+            <li><label><input type="radio" name="beatle" value="" /> ------</label></li>
             <li><label><input checked type="radio" name="beatle" value="J" /> John</label></li>
             <li><label><input type="radio" name="beatle" value="P" /> Paul</label></li>
             <li><label><input type="radio" name="beatle" value="G" /> George</label></li>
diff --git a/tests/forms_tests/widget_tests/test_widget.py b/tests/forms_tests/widget_tests/test_widget.py
index 3ad3c23a48..f25fe1e5fe 100644
--- a/tests/forms_tests/widget_tests/test_widget.py
+++ b/tests/forms_tests/widget_tests/test_widget.py
@@ -6,6 +6,13 @@ from .base import WidgetTest
 
 class WidgetTests(WidgetTest):
 
+    def test_format_value(self):
+        widget = Widget()
+        self.assertIsNone(widget.format_value(None))
+        self.assertIsNone(widget.format_value(''))
+        self.assertEqual(widget.format_value('español'), 'español')
+        self.assertEqual(widget.format_value(42.5), '42.5')
+
     def test_value_omitted_from_data(self):
         widget = Widget()
         self.assertIs(widget.value_omitted_from_data({}, {}, 'field'), True)