Presumably you'll eventually have enough transactions that you'll want
to start paging them. At that point, it would change how you would
arrive at the balance. If a user is looking at page 30, you shouldn't
need to retrieve the transactions from pages 1-29.
Eventually, you may want to consider something like this:
from django.db.models import Sum
PER_PAGE = 20
...
page = request.GET.get('page') or 1
start = (page - 1) * PER_PAGE
end = start + PER_PAGE
trans = Transaction.objects.order_by('date', 'id')[start:end]
earliest = trans[0]
qs = Transaction.objects.filter(date__lte=earliest.date,
id__lt=earliest.id)
previous = qs.aggregate(debit=Sum('debit'), credit=Sum('credit'))
balance = previous['debit']
balance -= previous['credit']
transaction_list = []
for tran in trans:
balance = balance + tran.debit
balance = balance - tran.credit
transaction_list.append({'transaction':tran,'balance':balance})
--Jeremy
--
You received this message because you are subscribed to the Google Groups
"Django users" group.
To post to this group, send email to django-us...@googlegroups.com.
To unsubscribe from this group, send email to
django-users+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/django-users?hl=en.
