Auto-check-in for specific sales channels (#1409)

* Autocheckin data model/cosmetics

* Expose automatically checked-in OrderPositions

* Expose automatically checked-in OrderPositions in CSV/PDF Exports

* Fix some tests, try to fix MultiStringField/CheckboxSelectMultiple

* Actually fix MultiStringField/CheckboxSelectMultiple.
(Not pretty, but it works)

* Fix more tests

* Squash migration

* Also fix CSV/nameparts-test

* Changes for Autocheckin code-review

* Perform Auto-Checkins through new core plugin

* Update config-doc to reflect also checkinlists

* Explicitly output AutoCheckin Yes/No for CSV-Export (+ fix test)

* Move autocheckin from plugin to service

* API-doc

* Fix API-doc spelling

* Checkinlist-API and autocheckin order tests

* Performance improvement when reading checkinlists for autocheckin

Co-Authored-By: Raphael Michel <michel@rami.io>

* Autocheckin test for order created through API

* Resolve migration conflict

src/pretix/base/models/checkin.py

@@ -5,6 +5,7 @@ from django.utils.translation import pgettext_lazy, ugettext_lazy as _
 from django_scopes import ScopedManager
 
 from pretix.base.models import LoggedModel
+from pretix.base.models.fields import MultiStringField
 
 
 class CheckinList(LoggedModel):
@@ -20,6 +21,15 @@ class CheckinList(LoggedModel):
                                                       'order have not been paid. This only works with pretixdesk '
                                                       '0.3.0 or newer or pretixdroid 1.9 or newer.'))
 
+    auto_checkin_sales_channels = MultiStringField(
+        default=[],
+        blank=True,
+        verbose_name=_('Sales channels to automatically check in'),
+        help_text=_('All items on this check-in list will be automatically marked as checked-in when purchased through '
+                    'any of the selected sales channels. This option can be useful when tickets sold at the box office '
+                    'are not checked again before entry and should be considered validated directly upon purchase.')
+    )
+
     objects = ScopedManager(organizer='event__organizer')
 
     class Meta:
@@ -87,6 +97,7 @@ class Checkin(models.Model):
     list = models.ForeignKey(
         'pretixbase.CheckinList', related_name='checkins', on_delete=models.PROTECT,
     )
+    auto_checked_in = models.BooleanField(default=False)
 
     objects = ScopedManager(organizer='position__order__event__organizer')