From 7a8f90478ada57cbb697a7ba3e7fb97d65d6e715 Mon Sep 17 00:00:00 2001
From: Raphael Michel <mail@raphaelmichel.de>
Date: Wed, 20 Jan 2021 17:26:47 +0100
Subject: [PATCH] CartAdd with subevents: Useful redirect in error case

---
 .../templates/pretixpresale/event/index.html      |  2 +-
 src/pretix/presale/views/cart.py                  | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/pretix/presale/templates/pretixpresale/event/index.html b/src/pretix/presale/templates/pretixpresale/event/index.html
index e29f343263..5dbca0addf 100644
--- a/src/pretix/presale/templates/pretixpresale/event/index.html
+++ b/src/pretix/presale/templates/pretixpresale/event/index.html
@@ -252,7 +252,7 @@
                     data-asynctask-headline="{% trans "We're now trying to reserve this for you!" %}"
                     data-asynctask-text="{% blocktrans with time=event.settings.reservation_time %}Once the items are in your cart, you will have {{ time }} minutes to complete your purchase.{% endblocktrans %}"
                     class="{% if event.seating_plan_id %}has-seating{% endif %}"
-                    action="{% eventurl request.event "presale:event.cart.add" cart_namespace=cart_namespace %}?next={{ cart_redirect|urlencode }}">
+                    action="{% eventurl request.event "presale:event.cart.add" cart_namespace=cart_namespace %}?next={{ cart_redirect|urlencode }}&next_error={{ request.path|urlencode }}">
                 {% csrf_token %}
                 <input type="hidden" name="subevent" value="{{ subevent.id|default_if_none:"" }}" />
                 {% if ev.seating_plan_id and event.settings.seating_choice %}
diff --git a/src/pretix/presale/views/cart.py b/src/pretix/presale/views/cart.py
index 517ca3690a..f188a0df5e 100644
--- a/src/pretix/presale/views/cart.py
+++ b/src/pretix/presale/views/cart.py
@@ -71,6 +71,19 @@ class CartActionMixin:
         return self.get_next_url()
 
     def get_error_url(self):
+        if "next_error" in self.request.GET and is_safe_url(self.request.GET.get("next_error"), allowed_hosts=None):
+            u = self.request.GET.get('next_error')
+            if '?' in u:
+                u += '&require_cookie=true'
+            else:
+                u += '?require_cookie=true'
+            disclose_cart_id = (
+                'iframe' in self.request.GET or settings.SESSION_COOKIE_NAME not in self.request.COOKIES
+            ) and self.kwargs.get('cart_namespace')
+            if disclose_cart_id:
+                cart_id = get_or_create_cart_id(self.request)
+                u += '&cart_id={}'.format(cart_id)
+            return u
         return self.get_next_url()
 
     @cached_property
@@ -413,6 +426,8 @@ class CartAdd(EventViewMixin, CartActionMixin, AsyncAction, View):
         u = super().get_check_url(task_id, ajax)
         if "next" in self.request.GET:
             u += "&next=" + quote(self.request.GET.get('next'))
+        if "next_error" in self.request.GET:
+            u += "&next_error=" + quote(self.request.GET.get('next_error'))
         if ajax:
             cart_id = get_or_create_cart_id(self.request)
             u += '&take_cart_id=' + cart_id