Fix last paid sorting

Bug #105. Rendering needs better formatting.

members/tables.py

@@ -2,15 +2,16 @@
 
 import django_tables2 as tables
 from django.utils.translation import ugettext as _
+from django.core.exceptions import ObjectDoesNotExist
+from django.db.models import F, OuterRef, Subquery
 
 from members.models import Member, Payment, Request
-from django.db.models import F
 
 
 class MemberTable(tables.Table):
     """Table for member."""
 
-    last_paid = tables.DateTimeColumn(verbose_name=_('Last paid'), order_by='payments.date')
+    last_paid = tables.DateTimeColumn(verbose_name=_('Last paid'))
 
     options = tables.TemplateColumn(
         ('<a class="data-table-button btn btn-primary" '
@@ -25,6 +26,19 @@ class MemberTable(tables.Table):
 
         model = Member
 
+    def render_last_paid(self, record):
+        try:
+            return record.payments.filter(member=record).latest('date').date.strftime('%e.%m.%Y %H:%M')
+        except ObjectDoesNotExist:
+            return record.created.strftime('%e.%m.%Y %H:%M') + _(" (not paid)")
+
+    def order_last_paid(self, queryset, is_descending):
+        latest = Payment.objects.filter(member=OuterRef('pk')).order_by('-date')
+        queryset = queryset.annotate(last_paid=Subquery(latest.values('date')[:1])
+            ).order_by(('-' if is_descending else '') + 'last_paid')
+        return (queryset, True)
+
+    
 
 class PaymentTable(tables.Table):
     """Table for payments."""