Refactor cancelling positions and orders in the data model (#1088)

- [x] Data model
- [x] display in order view in backend
- [x] review all usages of OrderPositions.objects
- [x] review all usages of order.positions
- [x] review all other model usages
- [x] review plugins
- [x] plugins backwards-compatible API?
- [x] decide on way forward for REST API
- [x] need to cancel fees
- [x] tests
- [ ] plugins
  - [ ] gdpr
  - [ ] reports
- [x] docs

src/pretix/base/services/checkin.py

@@ -78,7 +78,7 @@ def perform_checkin(op: OrderPosition, clist: CheckinList, given_answers: dict,
     dt = datetime or now()
 
     # Fetch order position with related objects
-    op = OrderPosition.objects.select_related(
+    op = OrderPosition.all.select_related(
         'item', 'variation', 'order', 'addon_to'
     ).prefetch_related(
         'item__questions',
@@ -90,6 +90,12 @@ def perform_checkin(op: OrderPosition, clist: CheckinList, given_answers: dict,
         'answers'
     ).get(pk=op.pk)
 
+    if op.canceled:
+        raise CheckInError(
+            _('This order position has been canceled.'),
+            'unpaid'
+        )
+
     answers = {a.question: a for a in op.answers.all()}
     require_answers = []
     for q in op.item.checkin_questions:

src/pretix/base/services/invoices.py

@@ -234,7 +234,7 @@ def generate_invoice(order: Order, trigger_pdf=True):
     if trigger_pdf:
         invoice_pdf(invoice.pk)
 
-    if order.status in (Order.STATUS_CANCELED, Order.STATUS_REFUNDED):
+    if order.status == Order.STATUS_CANCELED:
         generate_cancellation(invoice, trigger_pdf)
 
     return invoice

src/pretix/base/services/orders.py

@@ -124,25 +124,12 @@ def extend_order(order: Order, new_date: datetime, force: bool=False, user: User
 
 @transaction.atomic
 def mark_order_refunded(order, user=None, auth=None, api_token=None):
-    """
-    Mark this order as refunded. This sets the payment status and returns the order object.
-    :param order: The order to change
-    :param user: The user that performed the change
-    """
-    if isinstance(order, int):
-        order = Order.objects.get(pk=order)
-    if isinstance(user, int):
-        user = User.objects.get(pk=user)
-    with order.event.lock():
-        order.status = Order.STATUS_REFUNDED
-        order.save(update_fields=['status'])
-
-    order.log_action('pretix.event.order.refunded', user=user, auth=auth or api_token)
-    i = order.invoices.filter(is_cancellation=False).last()
-    if i:
-        generate_cancellation(i)
-
-    return order
+    oautha = auth.pk if isinstance(auth, OAuthApplication) else None
+    device = auth.pk if isinstance(auth, Device) else None
+    api_token = (api_token.pk if api_token else None) or (auth if isinstance(auth, TeamAPIToken) else None)
+    return _cancel_order(
+        order.pk, user.pk if user else None, send_mail=False, api_token=api_token, device=device, oauth_application=oautha
+    )
 
 
 @transaction.atomic
@@ -1043,7 +1030,10 @@ class OrderChangeManager:
                         'addon_to': opa.addon_to_id,
                         'old_price': opa.price,
                     })
-                    opa.delete()
+                    opa.canceled = True
+                    if opa.voucher:
+                        Voucher.objects.filter(pk=opa.voucher.pk).update(redeemed=F('redeemed') - 1)
+                    opa.save(update_fields=['canceled'])
                 self.order.log_action('pretix.event.order.changed.cancel', user=self.user, auth=self.auth, data={
                     'position': op.position.pk,
                     'positionid': op.position.positionid,
@@ -1052,7 +1042,10 @@ class OrderChangeManager:
                     'old_price': op.position.price,
                     'addon_to': None,
                 })
-                op.position.delete()
+                op.position.canceled = True
+                if op.position.voucher:
+                    Voucher.objects.filter(pk=op.position.voucher.pk).update(redeemed=F('redeemed') - 1)
+                op.position.save(update_fields=['canceled'])
             elif isinstance(op, self.AddOperation):
                 pos = OrderPosition.objects.create(
                     item=op.item, variation=op.variation, addon_to=op.addon_to,
@@ -1117,7 +1110,7 @@ class OrderChangeManager:
         except InvoiceAddress.DoesNotExist:
             pass
 
-        split_order.total = sum([p.price for p in split_positions])
+        split_order.total = sum([p.price for p in split_positions if not p.canceled])
         if split_order.total != Decimal('0.00') and self.order.status != Order.STATUS_PAID:
             pp = self._get_payment_provider()
             if pp:
@@ -1180,7 +1173,7 @@ class OrderChangeManager:
         return payment_sum - refund_sum
 
     def _recalculate_total_and_payment_fee(self):
-        total = sum([p.price for p in self.order.positions.all()]) + sum([f.value for f in self.order.fees.all()])
+        total = sum([p.price for p in self.order.positions.all() if not p.canceled]) + sum([f.value for f in self.order.fees.all()])
         payment_fee = Decimal('0.00')
         if self.open_payment:
             current_fee = Decimal('0.00')

src/pretix/base/services/stats.py

@@ -1,7 +1,7 @@
 from decimal import Decimal
 from typing import Any, Dict, Iterable, List, Tuple
 
-from django.db.models import Count, Sum
+from django.db.models import Case, Count, F, Sum, Value, When
 from django.utils.translation import ugettext_lazy as _
 
 from pretix.base.models import Event, Item, ItemCategory, Order, OrderPosition
@@ -79,18 +79,22 @@ def order_overview(event: Event, subevent: SubEvent=None) -> Tuple[List[Tuple[It
         'variations'
     ).order_by('category__position', 'category_id', 'position', 'name')
 
-    qs = OrderPosition.objects
+    qs = OrderPosition.all
     if subevent:
         qs = qs.filter(subevent=subevent)
     counters = qs.filter(
         order__event=event
+    ).annotate(
+        status=Case(
+            When(canceled=True, then=Value('c')),
+            default=F('order__status')
+        )
     ).values(
-        'item', 'variation', 'order__status'
+        'item', 'variation', 'status'
     ).annotate(cnt=Count('id'), price=Sum('price'), tax_value=Sum('tax_value')).order_by()
 
     states = {
         'canceled': Order.STATUS_CANCELED,
-        'refunded': Order.STATUS_REFUNDED,
         'paid': Order.STATUS_PAID,
         'pending': Order.STATUS_PENDING,
         'expired': Order.STATUS_EXPIRED,
@@ -99,7 +103,7 @@ def order_overview(event: Event, subevent: SubEvent=None) -> Tuple[List[Tuple[It
     for l, s in states.items():
         num[l] = {
             (p['item'], p['variation']): (p['cnt'], p['price'], p['price'] - p['tax_value'])
-            for p in counters if p['order__status'] == s
+            for p in counters if p['status'] == s
         }
 
     num['total'] = dictsum(num['pending'], num['paid'])
@@ -149,16 +153,21 @@ def order_overview(event: Event, subevent: SubEvent=None) -> Tuple[List[Tuple[It
     payment_items = []
 
     if not subevent:
-        counters = OrderFee.objects.filter(
+        counters = OrderFee.all.filter(
             order__event=event
+        ).annotate(
+            status=Case(
+                When(canceled=True, then=Value('c')),
+                default=F('order__status')
+            )
         ).values(
-            'fee_type', 'internal_type', 'order__status'
+            'fee_type', 'internal_type', 'status'
         ).annotate(cnt=Count('id'), value=Sum('value'), tax_value=Sum('tax_value')).order_by()
 
         for l, s in states.items():
             num[l] = {
                 (o['fee_type'], o['internal_type']): (o['cnt'], o['value'], o['value'] - o['tax_value'])
-                for o in counters if o['order__status'] == s
+                for o in counters if o['status'] == s
             }
         num['total'] = dictsum(num['pending'], num['paid'])