add extend_cart_reservation task and CartExtendReservation view

src/pretix/base/services/cart.py

@@ -1649,6 +1649,30 @@ def clear_cart(self, event: Event, cart_id: str=None, locale='en', sales_channel
             raise CartError(error_messages['busy'])
 
 
+@app.task(base=ProfiledEventTask, bind=True, max_retries=5, default_retry_delay=1, throws=(CartError,))
+def extend_cart_reservation(self, event: Event, cart_id: str=None, locale='en', sales_channel='web', override_now_dt: datetime=None) -> None:
+    """
+    Resets the expiry time of a cart to the configured reservation time of this event.
+    Limited to 11x the reservation time.
+
+    :param event: The event ID in question
+    :param cart_id: The cart ID of the cart to modify
+    """
+    with language(locale), time_machine_now_assigned(override_now_dt):
+        try:
+            sales_channel = event.organizer.sales_channels.get(identifier=sales_channel)
+        except SalesChannel.DoesNotExist:
+            raise CartError("Invalid sales channel.")
+        try:
+            try:
+                cm = CartManager(event=event, cart_id=cart_id, sales_channel=sales_channel)
+                cm.commit()
+            except LockTimeoutException:
+                self.retry()
+        except (MaxRetriesExceededError, LockTimeoutException):
+            raise CartError(error_messages['busy'])
+
+
 @app.task(base=ProfiledEventTask, bind=True, max_retries=5, default_retry_delay=1, throws=(CartError,))
 def set_cart_addons(self, event: Event, addons: List[dict], add_to_cart_items: List[dict], cart_id: str=None, locale='en',
                     invoice_address: int=None, sales_channel='web', override_now_dt: datetime=None) -> None:

src/pretix/presale/urls.py

@@ -56,6 +56,7 @@ frame_wrapped_urls = [
     re_path(r'^cart/remove$', pretix.presale.views.cart.CartRemove.as_view(), name='event.cart.remove'),
     re_path(r'^cart/voucher$', pretix.presale.views.cart.CartApplyVoucher.as_view(), name='event.cart.voucher'),
     re_path(r'^cart/clear$', pretix.presale.views.cart.CartClear.as_view(), name='event.cart.clear'),
+    re_path(r'^cart/extend$', pretix.presale.views.cart.CartExtendReservation.as_view(), name='event.cart.extend'),
     re_path(r'^cart/answer/(?P<answer>[^/]+)/$',
             pretix.presale.views.cart.AnswerDownload.as_view(),
             name='event.cart.download.answer'),

src/pretix/presale/views/cart.py

@@ -62,7 +62,7 @@ from pretix.base.models import (
 )
 from pretix.base.services.cart import (
     CartError, add_items_to_cart, apply_voucher, clear_cart, error_messages,
-    remove_cart_position,
+    extend_cart_reservation, remove_cart_position,
 )
 from pretix.base.timemachine import time_machine_now
 from pretix.base.views.tasks import AsyncAction
@@ -537,6 +537,19 @@ class CartClear(EventViewMixin, CartActionMixin, AsyncAction, View):
                        request.sales_channel.identifier, time_machine_now(default=None))
 
 
+@method_decorator(allow_frame_if_namespaced, 'dispatch')
+class CartExtendReservation(EventViewMixin, CartActionMixin, AsyncAction, View):
+    task = extend_cart_reservation
+    known_errortypes = ['CartError']
+
+    def get_success_message(self, value):
+        return _('Your cart timeout was extended.')
+
+    def post(self, request, *args, **kwargs):
+        return self.do(self.request.event.id, get_or_create_cart_id(self.request), translation.get_language(),
+                       request.sales_channel.identifier, time_machine_now(default=None))
+
+
 @method_decorator(allow_cors_if_namespaced, 'dispatch')
 @method_decorator(allow_frame_if_namespaced, 'dispatch')
 @method_decorator(iframe_entry_view_wrapper, 'dispatch')