Send signal on checkin (#1546)

* Send signal when orderposition is checked in

* Add position_checked_in signal to documentation

* Rename signal to checkin_created

* Update general.rst

* Update signals.py

Co-authored-by: Raphael Michel <mail@raphaelmichel.de>

src/pretix/base/services/checkin.py

@@ -7,7 +7,7 @@ from django.utils.translation import ugettext as _
 from pretix.base.models import (
     Checkin, CheckinList, Order, OrderPosition, Question, QuestionOption,
 )
-from pretix.base.signals import order_placed
+from pretix.base.signals import checkin_created, order_placed
 
 
 class CheckInError(Exception):
@@ -143,6 +143,7 @@ def perform_checkin(op: OrderPosition, clist: CheckinList, given_answers: dict,
                 'datetime': dt,
                 'list': clist.pk
             }, user=user, auth=auth)
+            checkin_created.send(op.order.event, checkin=ci)
     else:
         if not force:
             raise CheckInError(
@@ -171,4 +172,5 @@ def order_placed(sender, **kwargs):
     for op in order.positions.all():
         for cl in cls:
             if cl.all_products or op.item_id in {i.pk for i in cl.limit_products.all()}:
-                Checkin.objects.create(position=op, list=cl, auto_checked_in=True)
+                ci = Checkin.objects.create(position=op, list=cl, auto_checked_in=True)
+                checkin_created.send(event, checkin=ci)

src/pretix/base/signals.py

@@ -405,6 +405,17 @@ the deletion of the order.
 As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
 """
 
+checkin_created = EventPluginSignal(
+    providing_args=["checkin"],
+)
+"""
+This signal is sent out every time a check-in is created (i.e. an order position is marked as
+checked in). It is not send if the position was already checked in and is force-checked-in a second time.
+The check-in object is given as the first argument
+
+As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
+"""
+
 logentry_display = EventPluginSignal(
     providing_args=["logentry"]
 )