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. """ data = [] for bf in form: # Get the value from the form data. If the form allows empty or hasn't # changed then don't call clean() to avoid trigger validation errors. if form.empty_permitted and not form.has_changed(): value = bf.data or '' else: value = bf.field.clean(bf.data) or '' if isinstance(value, basestring): value = value.strip() data.append((bf.name, value)) 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()