Fixed #6209: handle BooleanFields in FormPreview and FormWizard. In the process, broke the the security hash calculation out to a helper function. Thanks to mcroydon and rajeshdhawan.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@8597 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/formtools/utils.py

@@ -0,0 +1,39 @@
+try:
+    import cPickle as pickle
+except ImportError:
+    import pickle
+    
+from django.conf import settings
+from django.utils.hashcompat import md5_constructor
+from django.forms import BooleanField
+
+def security_hash(request, form, *args):
+        """
+        Calculates a security hash for the given Form instance.
+
+        This creates a list of the form field names/values in a deterministic
+        order, pickles the result with the SECRET_KEY setting, then takes an md5
+        hash of that.
+        """
+        # Ensure that the hash does not change when a BooleanField's bound
+        # data is a string `False' or a boolean False.
+        # Rather than re-coding this special behaviour here, we
+        # create a dummy BooleanField and call its clean method to get a
+        # boolean True or False verdict that is consistent with
+        # BooleanField.clean()
+        dummy_bool = BooleanField(required=False)
+        def _cleaned_data(bf):
+            if isinstance(bf.field, BooleanField):
+                return dummy_bool.clean(bf.data)
+            return bf.data
+        
+        data = [(bf.name, _cleaned_data(bf) or '') for bf in form]
+        data.extend(args)
+        data.append(settings.SECRET_KEY)
+        
+        # Use HIGHEST_PROTOCOL because it's the most efficient. It requires
+        # Python 2.3, but Django requires 2.3 anyway, so that's OK.
+        pickled = pickle.dumps(data, pickle.HIGHEST_PROTOCOL)
+        
+        return md5_constructor(pickled).hexdigest()
+