'If this field is not declared readonly, the object\'s attribute will
be set to the value returned by :meth:`~import_export.fields.Field.clean`.'

def save(self, obj, data):

    if (not self.readonly):
        attrs = self.attribute.split(u'__')
        for attr in attrs[:(-1)]:
            obj = getattr(obj, attr, None)
        if ((self.clean(data) != None) or self.saves_null_values):
            setattr(obj, attrs[(-1)], self.clean(data))
