Cart expiry handling, checkout link

src/pretix/presale/views/checkout.py

@@ -0,0 +1,23 @@
+from django.contrib import messages
+from django.core.urlresolvers import reverse
+from django.shortcuts import redirect
+from django.views.generic import View
+from django.utils.translation import ugettext_lazy as _
+
+from pretix.presale.views import EventViewMixin, CartDisplayMixin
+
+
+class CheckoutStart(EventViewMixin, CartDisplayMixin, View):
+
+    def get_failure_url(self):
+        return reverse('presale:event.index', kwargs={
+            'event': self.request.event.slug,
+            'organizer': self.request.event.organizer.slug,
+        })
+
+    def get(self, *args, **kwargs):
+        cart = self.get_cart()
+        if not cart['positions']:
+            messages.error(self.request,
+                           _("Your cart is empty") % self.event.max_items_per_order)
+            return redirect(self.get_failure_url())