Fixed #22897 -- Made QueryDict query_string argument optional.

Now QueryDict() is equivalent to QueryDict('') or QueryDict(None).

django/http/request.py

@@ -317,7 +317,7 @@ class QueryDict(MultiValueDict):
     _mutable = True
     _encoding = None
 
-    def __init__(self, query_string, mutable=False, encoding=None):
+    def __init__(self, query_string=None, mutable=False, encoding=None):
         super(QueryDict, self).__init__()
         if not encoding:
             encoding = settings.DEFAULT_CHARSET

docs/ref/request-response.txt

@@ -355,13 +355,16 @@ Methods
 :class:`QueryDict` implements all the standard dictionary methods because it's
 a subclass of dictionary. Exceptions are outlined here:
 
-.. method:: QueryDict.__init__(query_string, mutable=False, encoding=None)
+.. method:: QueryDict.__init__(query_string=None, mutable=False, encoding=None)
 
    Instantiates a ``QueryDict`` object based on ``query_string``.
 
           >>> QueryDict('a=1&a=2&c=3')
           <QueryDict: {u'a': [u'1', u'2'], u'b': [u'1']}>
 
+   If ``query_string`` is not passed in, the resulting ``QueryDict`` will be
+   empty (it will have no keys or values).
+
    Most ``QueryDict``\ s you encounter, and in particular those at
    ``request.POST`` and ``request.GET``, will be immutable. If you are
    instantiating one yourself, you can make it mutable by passing
@@ -370,6 +373,10 @@ 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`.
 
+   .. versionchanged:: 1.8
+
+        In previous versions, ``query_string`` was a required positional argument.
+
 .. method:: QueryDict.__getitem__(key)
 
     Returns the value for the given key. If the key has more than one value,
@@ -523,7 +530,7 @@ In addition, ``QueryDict`` has the following methods:
     Optionally, urlencode can be passed characters which
     do not require encoding. For example::
 
-        >>> q = QueryDict('', mutable=True)
+        >>> q = QueryDict(mutable=True)
         >>> q['next'] = '/a&b/'
         >>> q.urlencode(safe='/')
         'next=/a%26b/'

docs/releases/1.8.txt

@@ -215,6 +215,11 @@ Requests and Responses
   :exc:`~django.core.exceptions.SuspiciousOperation`, the response will be
   rendered with a detailed error page.
 
+* The ``query_string`` argument of :class:`~django.http.QueryDict` is now
+  optional, defaulting to ``None``, so a blank ``QueryDict`` can now be
+  instantiated with ``QueryDict()`` instead of ``QueryDict(None)`` or
+  ``QueryDict('')``.
+
 Tests
 ^^^^^
 

tests/httpwrappers/tests.py

@@ -26,12 +26,15 @@ lazystr = lazy(force_text, six.text_type)
 
 
 class QueryDictTests(unittest.TestCase):
+    def test_create_with_no_args(self):
+        self.assertEqual(QueryDict(), QueryDict(str('')))
+
     def test_missing_key(self):
-        q = QueryDict(str(''))
+        q = QueryDict()
         self.assertRaises(KeyError, q.__getitem__, 'foo')
 
     def test_immutability(self):
-        q = QueryDict(str(''))
+        q = QueryDict()
         self.assertRaises(AttributeError, q.__setitem__, 'something', 'bar')
         self.assertRaises(AttributeError, q.setlist, 'foo', ['bar'])
         self.assertRaises(AttributeError, q.appendlist, 'foo', ['bar'])
@@ -41,11 +44,11 @@ class QueryDictTests(unittest.TestCase):
         self.assertRaises(AttributeError, q.clear)
 
     def test_immutable_get_with_default(self):
-        q = QueryDict(str(''))
+        q = QueryDict()
         self.assertEqual(q.get('foo', 'default'), 'default')
 
     def test_immutable_basic_operations(self):
-        q = QueryDict(str(''))
+        q = QueryDict()
         self.assertEqual(q.getlist('foo'), [])
         if six.PY2:
             self.assertEqual(q.has_key('foo'), False)
@@ -95,30 +98,30 @@ class QueryDictTests(unittest.TestCase):
         self.assertEqual(q.urlencode(), 'foo=bar')
 
     def test_urlencode(self):
-        q = QueryDict(str(''), mutable=True)
+        q = QueryDict(mutable=True)
         q['next'] = '/a&b/'
         self.assertEqual(q.urlencode(), 'next=%2Fa%26b%2F')
         self.assertEqual(q.urlencode(safe='/'), 'next=/a%26b/')
-        q = QueryDict(str(''), mutable=True)
+        q = QueryDict(mutable=True)
         q['next'] = '/t\xebst&key/'
         self.assertEqual(q.urlencode(), 'next=%2Ft%C3%ABst%26key%2F')
         self.assertEqual(q.urlencode(safe='/'), 'next=/t%C3%ABst%26key/')
 
     def test_mutable_copy(self):
         """A copy of a QueryDict is mutable."""
-        q = QueryDict(str('')).copy()
+        q = QueryDict().copy()
         self.assertRaises(KeyError, q.__getitem__, "foo")
         q['name'] = 'john'
         self.assertEqual(q['name'], 'john')
 
     def test_mutable_delete(self):
-        q = QueryDict(str('')).copy()
+        q = QueryDict(mutable=True)
         q['name'] = 'john'
         del q['name']
         self.assertFalse('name' in q)
 
     def test_basic_mutable_operations(self):
-        q = QueryDict(str('')).copy()
+        q = QueryDict(mutable=True)
         q['name'] = 'john'
         self.assertEqual(q.get('foo', 'default'), 'default')
         self.assertEqual(q.get('name', 'default'), 'john')
@@ -210,7 +213,7 @@ class QueryDictTests(unittest.TestCase):
             self.assertEqual(q.getlist('foo'), ['bar', '\ufffd'])
 
     def test_pickle(self):
-        q = QueryDict(str(''))
+        q = QueryDict()
         q1 = pickle.loads(pickle.dumps(q, 2))
         self.assertEqual(q == q1, True)
         q = QueryDict(str('a=b&c=d'))