Fixed #17210 -- Made NullBooleanSelect use unknown/true/false as query data.

1 files changed, 15 insertions, 7 deletions

diff --git a/django/forms/widgets.py b/django/forms/widgets.py
index e4f8957189..eed1fa5c3b 100644
--- a/django/forms/widgets.py
+++ b/django/forms/widgets.py
@@ -696,27 +696,35 @@ class NullBooleanSelect(Select):
     """
     def __init__(self, attrs=None):
         choices = (
-            ('1', _('Unknown')),
-            ('2', _('Yes')),
-            ('3', _('No')),
+            ('unknown', _('Unknown')),
+            ('true', _('Yes')),
+            ('false', _('No')),
         )
         super().__init__(attrs, choices)
 
     def format_value(self, value):
         try:
-            return {True: '2', False: '3', '2': '2', '3': '3'}[value]
+            return {
+                True: 'true', False: 'false',
+                'true': 'true', 'false': 'false',
+                # For backwards compatibility with Django < 2.2.
+                '2': 'true', '3': 'false',
+            }[value]
         except KeyError:
-            return '1'
+            return 'unknown'
 
     def value_from_datadict(self, data, files, name):
         value = data.get(name)
         return {
-            '2': True,
             True: True,
             'True': True,
-            '3': False,
             'False': False,
             False: False,
+            'true': True,
+            'false': False,
+            # For backwards compatibility with Django < 2.2.
+            '2': True,
+            '3': False,
         }.get(value)