'First step of ExpressCheckout. Redirect the request to PayPal using the
data returned from setExpressCheckout.'

def redirect_to_express(self):

    wpp = PayPalWPP(self.request)
    try:
        nvp_obj = wpp.setExpressCheckout(self.item)
    except PayPalFailure:
        self.context['errors'] = self.errors['paypal']
        return self.render_payment_form()
    else:
        pp_params = dict(token=nvp_obj.token)
        pp_url = (self.get_endpoint() % urlencode(pp_params))
        return HttpResponseRedirect(pp_url)
