Fixed #26707 -- Added QueryDict.fromkeys()

AUTHORS

@@ -771,6 +771,7 @@ answer newbie questions, and generally made Django that much better:
     William Schwartz <wkschwartz@gmail.com>
     Will Hardy <django@willhardy.com.au>
     Wilson Miner <wminer@gmail.com>
+    Wim Glenn <hey@wimglenn.com>
     wojtek
     Xia Kai <http://blog.xiaket.org/>
     Yann Fouillat <gagaro42@gmail.com>

django/http/request.py

@@ -402,6 +402,19 @@ class QueryDict(MultiValueDict):
                                 value)
         self._mutable = mutable
 
+    @classmethod
+    def fromkeys(cls, iterable, value='', mutable=False, encoding=None):
+        """
+        Return a new QueryDict with keys (may be repeated) from an iterable and
+        values from value.
+        """
+        q = cls('', mutable=True, encoding=encoding)
+        for key in iterable:
+            q.appendlist(key, value)
+        if not mutable:
+            q._mutable = False
+        return q
+
     @property
     def encoding(self):
         if self._encoding is None:

docs/ref/request-response.txt

@@ -422,6 +422,16 @@ a subclass of dictionary. Exceptions are outlined here:
     Strings for setting both keys and values will be converted from ``encoding``
     to unicode. If encoding is not set, it defaults to :setting:`DEFAULT_CHARSET`.
 
+.. classmethod:: QueryDict.fromkeys(iterable, value='', mutable=False, encoding=None)
+
+    .. versionadded:: 1.11
+
+    Creates a new ``QueryDict`` with keys from ``iterable`` and each value
+    equal to ``value``. For example::
+
+        >>> QueryDict.fromkeys(['a', 'a', 'b'], value='val')
+        <QueryDict: {'a': ['val', 'val'], 'b': ['val']}>
+
 .. method:: QueryDict.__getitem__(key)
 
     Returns the value for the given key. If the key has more than one value,

docs/releases/1.11.txt

@@ -187,7 +187,7 @@ Models
 Requests and Responses
 ~~~~~~~~~~~~~~~~~~~~~~
 
-* ...
+* Added :meth:`QueryDict.fromkeys() <django.http.QueryDict.fromkeys>`.
 
 Serialization
 ~~~~~~~~~~~~~

tests/httpwrappers/tests.py

@@ -25,7 +25,7 @@ from django.utils.encoding import force_str
 from django.utils.functional import lazystr
 
 
-class QueryDictTests(unittest.TestCase):
+class QueryDictTests(SimpleTestCase):
     def test_create_with_no_args(self):
         self.assertEqual(QueryDict(), QueryDict(str('')))
 
@@ -271,6 +271,44 @@ class QueryDictTests(unittest.TestCase):
         self.assertEqual(copy.copy(q).encoding, 'iso-8859-15')
         self.assertEqual(copy.deepcopy(q).encoding, 'iso-8859-15')
 
+    def test_querydict_fromkeys(self):
+        self.assertEqual(QueryDict.fromkeys(['key1', 'key2', 'key3']), QueryDict('key1&key2&key3'))
+
+    def test_fromkeys_with_nonempty_value(self):
+        self.assertEqual(
+            QueryDict.fromkeys(['key1', 'key2', 'key3'], value='val'),
+            QueryDict('key1=val&key2=val&key3=val')
+        )
+
+    def test_fromkeys_is_immutable_by_default(self):
+        # Match behavior of __init__() which is also immutable by default.
+        q = QueryDict.fromkeys(['key1', 'key2', 'key3'])
+        with self.assertRaisesMessage(AttributeError, 'This QueryDict instance is immutable'):
+            q['key4'] = 'nope'
+
+    def test_fromkeys_mutable_override(self):
+        q = QueryDict.fromkeys(['key1', 'key2', 'key3'], mutable=True)
+        q['key4'] = 'yep'
+        self.assertEqual(q, QueryDict('key1&key2&key3&key4=yep'))
+
+    def test_duplicates_in_fromkeys_iterable(self):
+        self.assertEqual(QueryDict.fromkeys('xyzzy'), QueryDict('x&y&z&z&y'))
+
+    def test_fromkeys_with_nondefault_encoding(self):
+        key_utf16 = b'\xff\xfe\x8e\x02\xdd\x01\x9e\x02'
+        value_utf16 = b'\xff\xfe\xdd\x01n\x00l\x00P\x02\x8c\x02'
+        q = QueryDict.fromkeys([key_utf16], value=value_utf16, encoding='utf-16')
+        expected = QueryDict('', mutable=True)
+        expected['ʎǝʞ'] = 'ǝnlɐʌ'
+        self.assertEqual(q, expected)
+
+    def test_fromkeys_empty_iterable(self):
+        self.assertEqual(QueryDict.fromkeys([]), QueryDict(''))
+
+    def test_fromkeys_noniterable(self):
+        with self.assertRaises(TypeError):
+            QueryDict.fromkeys(0)
+
 
 class HttpResponseTests(unittest.TestCase):