Fixed #16393 -- FormWizard's cookie storage backend now works with all...

from django.core.files.uploadedfile import UploadedFile

from django.utils.functional import lazy_property

from django.utils.datastructures import MultiValueDict

from django.utils.encoding import smart_str

from django.utils.functional import lazy_property

from django.contrib.formtools.wizard.storage.exceptions import NoFileStorageConfigured

class BaseStorage(object):

    step_key = 'step'

    step_data_key = 'step_data'

    extra_data = lazy_property(_get_extra_data, _set_extra_data)

    def get_step_data(self, step):

        return self.data[self.step_data_key].get(step, None)

        # 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