Show number of paid members in member list

Member filtering also applies to this feature. Moved 'last_paid' Subquery to Member method

members/models.py

@@ -3,8 +3,7 @@
 from django.db import models
 from django.utils import timezone
 from django.utils.translation import ugettext_lazy as _
-from django.db.models import Q
-
+from django.db.models import Q, F, OuterRef, Subquery
 import csv
 
 
@@ -126,5 +125,11 @@ class Member(BaseMember):
         return qs
 
 
+    def get_members_with_latest_payment(members_query):
+        """Return QuerySet of given members QS with last_paid attribute."""
+        latest = Payment.objects.filter(member=OuterRef('pk')).order_by('-date')
+        return members_query.annotate(last_paid=Subquery(latest.values('date')[:1]))
+
+
 # To avoid problems with a cyclical import, this is at the bottom of the file
 from members.forms import MemberForm  # nopep8