Fix #297 -- pretixdroid: Show metrics in the control panel (#481)

* add checkin status page

add dashboard widget
add checkin page under orders

* modify checkin logic

added new fields in checkin page
added filter items

* add tests for checkins & minor improvement

* support addin_product & noadm setting logic

* remove name ordering check test case

src/pretix/control/views/checkin.py

@@ -0,0 +1,79 @@
+from django.db.models import Prefetch, Q
+from django.db.models.functions import Coalesce
+from django.views.generic import ListView
+
+from pretix.base.models import Checkin, Item, OrderPosition
+from pretix.control.permissions import EventPermissionRequiredMixin
+
+
+class CheckInView(EventPermissionRequiredMixin, ListView):
+    model = Checkin
+    context_object_name = 'entries'
+    paginate_by = 30
+    template_name = 'pretixcontrol/checkin/index.html'
+    permission = 'can_view_orders'
+
+    def get_queryset(self):
+
+        qs = OrderPosition.objects.filter(order__event=self.request.event, order__status='p')
+
+        # if this setting is False, we check only items for admission
+        if not self.request.event.settings.ticket_download_nonadm:
+            qs = qs.filter(item__admission=True)
+
+        if self.request.GET.get("status", "") != "":
+            p = self.request.GET.get("status", "")
+            if p == '1':
+                # records with check-in record
+                qs = qs.filter(checkins__isnull=False)
+            elif p == '0':
+                qs = qs.filter(checkins__isnull=True)
+
+        if self.request.GET.get("user", "") != "":
+            u = self.request.GET.get("user", "")
+            qs = qs.filter(
+                Q(order__email__icontains=u) | Q(attendee_name__icontains=u) | Q(attendee_email__icontains=u)
+            )
+
+        if self.request.GET.get("item", "") != "":
+            u = self.request.GET.get("item", "")
+            qs = qs.filter(item_id__in=(u,))
+
+        qs = qs.prefetch_related(
+            Prefetch('checkins', queryset=Checkin.objects.filter(position__order__event=self.request.event))
+        ).select_related('order', 'item', 'addon_to')
+
+        if self.request.GET.get("ordering", "") != "":
+            p = self.request.GET.get("ordering", "")
+            keys_allowed = self.get_ordering_keys_mappings()
+            if p in keys_allowed:
+                mapped_field = keys_allowed[p]
+                if type(mapped_field) is tuple:
+                    qs = qs.annotate(**mapped_field[1]).order_by(mapped_field[0])
+                else:
+                    qs = qs.order_by(mapped_field)
+
+        return qs.distinct()
+
+    def get_context_data(self, **kwargs):
+        ctx = super().get_context_data(**kwargs)
+        ctx['items'] = Item.objects.filter(event=self.request.event)
+        ctx['filtered'] = ("status" in self.request.GET or "user" in self.request.GET or "item" in self.request.GET)
+        return ctx
+
+    @staticmethod
+    def get_ordering_keys_mappings():
+        return {
+            'code': 'order__code',
+            '-code': '-order__code',
+            'email': 'order__email',
+            '-email': '-order__email',
+            'status': 'checkins__id',
+            '-status': '-checkins__id',
+            'timestamp': 'checkins__datetime',
+            '-timestamp': '-checkins__datetime',
+            'item': 'item__name',
+            '-item': '-item__name',
+            'name': ('display_name', {'display_name': Coalesce('attendee_name', 'addon_to__attendee_name')}),
+            '-name': ('-display_name', {'display_name': Coalesce('attendee_name', 'addon_to__attendee_name')}),
+        }