Fixed localization and error reporting with exceptions thrown in celery

src/pretix/base/i18n.py

@@ -342,3 +342,16 @@ def language(lng):
         yield
     finally:
         translation.activate(_lng)
+
+
+class LazyLocaleException(Exception):
+    def __init__(self, msg, msgargs=None):
+        self.msg = msg
+        self.msgargs = msgargs
+        super().__init__(msg, msgargs)
+
+    def __str__(self):
+        if self.msgargs:
+            return ugettext(self.msg) % self.msgargs
+        else:
+            return ugettext(self.msg)

src/pretix/base/services/cart.py

@@ -1,18 +1,18 @@
 from datetime import datetime, timedelta
 
 from django.conf import settings
-from django.db import transaction
 from django.db.models import Q
 from django.utils.timezone import now
 from django.utils.translation import ugettext_lazy as _
 from typing import List, Optional, Tuple
 
+from pretix.base.i18n import LazyLocaleException
 from pretix.base.models import (
     CartPosition, Event, EventLock, Item, ItemVariation, Quota, Voucher,
 )
 
 
-class CartError(Exception):
+class CartError(LazyLocaleException):
     pass
 
 
@@ -168,7 +168,7 @@ def _add_items_to_cart(event: Event, items: List[Tuple[int, Optional[int], int]]
         existing = CartPosition.objects.filter(Q(cart_id=cart_id) & Q(event=event)).count()
         if sum(i[2] for i in items) + existing > int(event.settings.max_items_per_order):
             # TODO: i18n plurals
-            raise CartError(error_messages['max_items'] % event.settings.max_items_per_order)
+            raise CartError(error_messages['max_items'], (event.settings.max_items_per_order,))
 
         expiry = now() + timedelta(minutes=event.settings.get('reservation_time', as_type=int))
         _extend_existing(event, cart_id, expiry)
@@ -232,22 +232,28 @@ def remove_items_from_cart(event: int, items: List[Tuple[int, Optional[int], int
 if settings.HAS_CELERY:
     from pretix.celery import app
 
-    @app.task(bind=True, max_retries=5, default_retry_delay=2)
+    @app.task(bind=True, max_retries=5, default_retry_delay=1)
     def add_items_to_cart_task(self, event: int, items: List[Tuple[int, Optional[int], int]], cart_id: str,
                                voucher: str=None):
         event = Event.objects.get(id=event)
         try:
-            _add_items_to_cart(event, items, cart_id, voucher)
+            try:
-        except EventLock.LockTimeoutException:
+                _add_items_to_cart(event, items, cart_id, voucher)
-            self.retry(exc=CartError(error_messages['busy']))
+            except EventLock.LockTimeoutException:
+                self.retry(exc=CartError(error_messages['busy']))
+        except CartError as e:
+            return e
 
-    @app.task(bind=True, max_retries=5, default_retry_delay=2)
+    @app.task(bind=True, max_retries=5, default_retry_delay=1)
     def remove_items_from_cart_task(self, event: int, items: List[Tuple[int, Optional[int], int]], cart_id: str):
         event = Event.objects.get(id=event)
         try:
-            _remove_items_from_cart(event, items, cart_id)
+            try:
-        except EventLock.LockTimeoutException:
+                _remove_items_from_cart(event, items, cart_id)
-            self.retry(exc=CartError(error_messages['busy']))
+            except EventLock.LockTimeoutException:
+                self.retry(exc=CartError(error_messages['busy']))
+        except CartError as e:
+            return e
 
     add_items_to_cart.task = add_items_to_cart_task
     remove_items_from_cart.task = remove_items_from_cart_task

src/pretix/base/services/orders.py

@@ -7,7 +7,9 @@ from django.utils.timezone import now
 from django.utils.translation import ugettext_lazy as _
 from typing import List
 
-from pretix.base.i18n import LazyDate, LazyNumber, language
+from pretix.base.i18n import (
+    LazyDate, LazyLocaleException, LazyNumber, language,
+)
 from pretix.base.models import (
     CartPosition, Event, EventLock, Order, OrderPosition, Quota, User,
 )
@@ -29,7 +31,6 @@ error_messages = {
                  'the quantity you selected. Please see below for details.'),
     'price_changed': _('The price of some of the items in your cart has changed in the '
                        'meantime. Please see below for details.'),
-    'max_items': _("You cannot select more than %s items per order"),
     'internal': _("An internal error occured, please try again."),
     'busy': _('We were not able to process your request completely as the '
               'server was too busy. Please try again.'),
@@ -142,7 +143,7 @@ def cancel_order(order, user=None):
     return order
 
 
-class OrderError(Exception):
+class OrderError(LazyLocaleException):
     pass
 
 
@@ -315,20 +316,26 @@ def perform_order(event: str, payment_provider: str, positions: List[str],
 if settings.HAS_CELERY:
     from pretix.celery import app
 
-    @app.task(bind=True, max_retries=5, default_retry_delay=2)
+    @app.task(bind=True, max_retries=5, default_retry_delay=1)
     def perform_order_task(self, event: str, payment_provider: str, positions: List[str],
                            email: str=None, locale: str=None, address: int=None):
         try:
-            return _perform_order(event, payment_provider, positions, email, locale, address)
+            try:
-        except EventLock.LockTimeoutException:
+                return _perform_order(event, payment_provider, positions, email, locale, address)
-            self.retry(exc=OrderError(error_messages['busy']))
+            except EventLock.LockTimeoutException:
+                self.retry(exc=OrderError(error_messages['busy']))
+        except OrderError as e:
+            return e
 
-    @app.task(bind=True, max_retries=5, default_retry_delay=2)
+    @app.task(bind=True, max_retries=5, default_retry_delay=1)
     def cancel_order_task(self, order: int, user: int=None):
         try:
-            return cancel_order(order, user)
+            try:
-        except EventLock.LockTimeoutException:
+                return cancel_order(order, user)
-            self.retry(exc=OrderError(error_messages['busy']))
+            except EventLock.LockTimeoutException:
+                self.retry(exc=OrderError(error_messages['busy']))
+        except OrderError as e:
+            return e
 
     perform_order.task = perform_order_task
     cancel_order.task = cancel_order_task

src/pretix/presale/views/async.py

@@ -48,7 +48,7 @@ class AsyncAction:
                 'ready': res.ready()
             }
             if res.ready():
-                if res.successful():
+                if res.successful() and not isinstance(res.info, Exception):
                     smes = self.get_success_message(res.info)
                     if smes:
                         messages.success(self.request, smes)