Do not create duplicate memberships on order changes (Z#23163336) (#4408)

src/pretix/base/services/orders.py

@@ -3152,7 +3152,7 @@ def signal_listener_issue_memberships(sender: Event, order: Order, **kwargs):
     if order.status != Order.STATUS_PAID or not order.customer:
         return
     for p in order.positions.all():
-        if p.item.grant_membership_type_id:
+        if p.item.grant_membership_type_id and not p.granted_memberships.exists():
             create_membership(order.customer, p)
 
 

src/pretix/control/templates/pretixcontrol/order/change.html

@@ -151,6 +151,12 @@
                             </div>
                             <div class="col-sm-4">
                                 {% bootstrap_field position.form.itemvar layout='inline' %}
+                                {% if position.granted_memberships.all %}
+                                    <span class="text-muted">
+                                        <span class="fa fa-warning text-warning" aria-hidden="true"></span>
+                                        {% trans "The sale of this position created a membership. Changing the product here will not affect the membership. Memberships can be managed in the customer account." %}
+                                    </span>
+                                {% endif %}
                             </div>
                         </div>
 
@@ -254,6 +260,12 @@
                                     {% trans "–" %}
                                 </div>
                                 {% bootstrap_field position.form.valid_until layout='inline' %}
+                                {% if position.granted_memberships.all %}
+                                    <span class="text-muted">
+                                        <span class="fa fa-warning text-warning" aria-hidden="true"></span>
+                                        {% trans "The sale of this position created a membership. Changing the validity of the ticket here will not affect the membership. Memberships can be managed in the customer account." %}
+                                    </span>
+                                {% endif %}
                             </div>
                         </div>
 

src/pretix/control/views/orders.py

@@ -1900,7 +1900,7 @@ class OrderChange(OrderView):
         positions = list(self.order.positions.select_related(
             'item', 'item__tax_rule', 'used_membership', 'used_membership__membership_type', 'tax_rule',
             'seat', 'subevent',
-        ))
+        ).prefetch_related('granted_memberships'))
         for p in positions:
             p.form = OrderPositionChangeForm(prefix='op-{}'.format(p.pk), instance=p, items=self.items,
                                              initial={'seat': p.seat.seat_guid if p.seat else None},

src/tests/base/test_orders.py

@@ -1662,7 +1662,7 @@ class OrderChangeManagerTests(TestCase):
         mt = self.event.organizer.membership_types.create(name="foo")
         customer = self.event.organizer.customers.create()
         self.order.customer = customer
-        self.o.save()
+        self.order.save()
         m = customer.memberships.create(
             membership_type=mt,
             date_start=now(),
@@ -1674,6 +1674,37 @@ class OrderChangeManagerTests(TestCase):
         m.refresh_from_db()
         assert m.canceled
 
+    @classscope(attr='o')
+    def test_create_membership_after_change(self):
+        mt = self.event.organizer.membership_types.create(name="foo")
+        customer = self.event.organizer.customers.create()
+        self.ticket.grant_membership_type = mt
+        self.ticket.save()
+        self.ticket2.grant_membership_type = mt
+        self.ticket2.save()
+        self.order.customer = customer
+        self.order.status = Order.STATUS_PAID
+        self.order.save()
+        assert customer.memberships.count() == 0
+        self.ocm.change_item(self.op1, item=self.ticket2, variation=None)
+        self.ocm.cancel(self.op2)
+        self.ocm.commit()
+
+        self.order.refresh_from_db()
+        self.op1.refresh_from_db()
+        customer.refresh_from_db()
+        assert self.op1.granted_memberships.count() == 1
+        assert customer.memberships.count() == 1
+
+        # But only once
+        self.ocm = OrderChangeManager(self.order, None)
+        self.ocm.change_item(self.op1, item=self.ticket, variation=None)
+        self.ocm.commit()
+
+        customer.refresh_from_db()
+        assert self.op1.granted_memberships.count() == 1
+        assert customer.memberships.count() == 1
+
     @classscope(attr='o')
     def test_cancel_issued_giftcard_used(self):
         gc = self.o.issued_gift_cards.create(currency="EUR", issued_in=self.op1)