Add sub-events and relative date settings (#503)

* Data model

* little crud

* SubEventItemForm etc

* Drop SubEventItem.active, quota editor

* Fix failing tests

* First frontend stuff

* Addons form stuff

* Quota calculation

* net price display on EventIndex

* Add tests, solve some bugs

* Correct quota selection in more places, consolidate pricing logic

* Fix failing quota tests

* Fix TypeError

* Add tests for checkout

* Fixed a bug in QuotaForm

* Prevent immutable cart if a quota was removed from an item

* Add tests for pricing

* Handle waiting list

* Filter in check-in list

* Fixed import lost in rebase

* Fix waiting list widget

* Voucher management

* Voucher redemption

* Fix broken tests

* Add subevents to OrderChangeManager

* Create a subevent during event creation

* Fix bulk voucher creation

* Introduce subevent.active

* Copy from for subevents

* Show active in list

* ICal download for subevents

* Check start and end of presale

* Failing tests / show cart logic

* Test

* Rebase migrations

* REST API integration of sub-events

* Integrate quota calculation into the traditional quota form

* Make subevent argument to add_position optional

* Log-display foo

* pretixdroid and subevents

* Filter by subevent

* Add more tests

* Some mor tests

* Rebase fixes

* More tests

* Relative dates

* Restrict selection in relative datetime widgets

* Filter subevent list

* Re-label has_subevents

* Rebase fixes, subevents in calendar view

* Performance and caching issues

* Refactor calendar templates

* Permission tests

* Calendar fixes and month selection

* subevent selection

* Rename subevents to dates

* Add tests for calendar views

src/pretix/presale/views/waiting.py

@@ -1,10 +1,12 @@
 from django.contrib import messages
-from django.shortcuts import redirect
+from django.shortcuts import get_object_or_404, redirect
 from django.utils import translation
 from django.utils.functional import cached_property
-from django.utils.translation import ugettext_lazy as _
+from django.utils.translation import pgettext_lazy, ugettext_lazy as _
 from django.views.generic import FormView
 
+from pretix.base.models.event import SubEvent
+
 from ...base.models import Item, ItemVariation, WaitingListEntry
 from ...multidomain.urlreverse import eventreverse
 from ..forms.waitinglist import WaitingListForm
@@ -19,13 +21,15 @@ class WaitingView(FormView):
         kwargs['event'] = self.request.event
         kwargs['instance'] = WaitingListEntry(
             item=self.item_and_variation[0], variation=self.item_and_variation[1],
-            event=self.request.event, locale=translation.get_language()
+            event=self.request.event, locale=translation.get_language(),
+            subevent=self.subevent
         )
         return kwargs
 
     def get_context_data(self, **kwargs):
         ctx = super().get_context_data()
         ctx['event'] = self.request.event
+        ctx['subevent'] = self.subevent
         ctx['item'], ctx['variation'] = self.item_and_variation
         return ctx
 
@@ -54,13 +58,22 @@ class WaitingView(FormView):
             messages.error(request, _("We could not identify the product you selected."))
             return redirect(eventreverse(self.request.event, 'presale:event.index'))
 
+        self.subevent = None
+        if request.event.has_subevents:
+            if 'subevent' in request.GET:
+                self.subevent = get_object_or_404(SubEvent, event=request.event, pk=request.GET['subevent'],
+                                                  active=True)
+            else:
+                messages.error(request, pgettext_lazy('subevent', "You need to select a date."))
+                return redirect(eventreverse(self.request.event, 'presale:event.index'))
+
         return super().dispatch(request, *args, **kwargs)
 
     def form_valid(self, form):
         availability = (
-            self.item_and_variation[1].check_quotas(count_waitinglist=False)
+            self.item_and_variation[1].check_quotas(count_waitinglist=False, subevent=self.subevent)
             if self.item_and_variation[1]
-            else self.item_and_variation[0].check_quotas(count_waitinglist=False)
+            else self.item_and_variation[0].check_quotas(count_waitinglist=False, subevent=self.subevent)
         )
         if availability[0] == 100:
             messages.error(self.request, _("You cannot add yourself to the waiting list as this product is currently "