if not self.cleaned_data['books'] and not self.cleaned_data['audiobooks']:
msg = ugettext(u"One of these fields is required.")
self._errors["books"] = self.error_class([msg])
self._errors["audiobooks"] = self.error_class([msg])
if not self.cleaned_data['books'] and not self.cleaned_data['audiobooks']:
msg = ugettext(u"One of these fields is required.")
self._errors["books"] = self.error_class([msg])
self._errors["audiobooks"] = self.error_class([msg])