Custom Django SessionStorage. Removed all the functionality that dealt with files. Based on Django-1.4's django.contrib.formtools.wizard.storage.base.BaseStorage django.contrib.formtools.wizard.storage.session.SessionStorage.

sessionstorage.py

from django.utils.datastructures import MultiValueDict


class SessionStorage(object):
	"""Custom SessionStorage class. Removed all the functionality that dealt
	with files.

	Based in Django-1.4's:
		`django.contrib.formtools.wizard.storage.base.BaseStorage`
		`django.contrib.formtools.wizard.storage.session.SessionStorage`

	"""
	step_key = 'step'
	step_data_key = 'step_data'
	extra_data_key = 'extra_data'

	def __init__(self, prefix, request=None):
		self.prefix = 'wizard_%s' % prefix
		self.request = request

		if self.prefix not in self.request.session:
			self.init_data()

	def init_data(self):
		self.data = {
			self.step_key: None,
			self.step_data_key: {},
			self.extra_data_key: {},
		}

	def _get_data(self):
		self.request.session.modified = True
		return self.request.session[self.prefix]

	def _set_data(self, value):
		self.request.session[self.prefix] = value
		self.request.session.modified = True

	data = property(_get_data, _set_data)

	def reset(self):
		self.init_data()

	def _get_current_step(self):
		return self.data[self.step_key]

	def _set_current_step(self, step):
		self.data[self.step_key] = step

	current_step = property(_get_current_step, _set_current_step)

	def _get_extra_data(self):
		return self.data[self.extra_data_key] or {}

	def _set_extra_data(self, extra_data):
		self.data[self.extra_data_key] = extra_data

	extra_data = property(_get_extra_data, _set_extra_data)

	def get_step_data(self, step):
		# When reading the serialized data, upconvert it to a MultiValueDict,
		# some serializers (json) don't preserve the type of the object.
		values = self.data[self.step_data_key].get(step, None)
		if values is not None:
			values = MultiValueDict(values)
		return values

	def set_step_data(self, step, cleaned_data):
		# If the value is a MultiValueDict, convert it to a regular dict of the
		# underlying contents.  Some serializers call the public API on it (as
		# opposed to the underlying dict methods), in which case the content
		# can be truncated (__getitem__ returns only the first item).
		if isinstance(cleaned_data, MultiValueDict):
			cleaned_data = dict(cleaned_data.lists())
		self.data[self.step_data_key][step] = cleaned_data

	@property
	def current_step_data(self):
		return self.get_step_data(self.current_step)

Awesome file!