Handling NoneType when using addition

Im trying to add some values up but some of the values have a NoneType value. Now I looked at this question but I need some help. Im hoping someone can explain to me how I can get this to work with django.

Here is my for loop in my views.py:

next_il = Investment.objects.all().filter(plan = plan).order_by('financial_institution').filter(maturity_date__year=next_ye开发者_StackOverflowar)
for inv in next_il:
   total_m2 += inv.maturity_amount

Now inv.maturity_amount is the value I'm trying to handle that has NoneType.

Any suggestions would be greatly appreciated.

Thanks.

Steve

---

for inv in next_il:
   total_m2 += inv.maturity_amount or 0

And may be you should set default=0 for maturity_amount field.

And it's better to use DB aggregation here:

from django.db.models import Sum

total_m2 = Investment.objects.filter(plan = plan).order_by('financial_institution').filter(maturity_date__year=next_year).aggregate(Sum('maturity_amount'))

---

Two choices that occur to me.

next_il = Investment.objects.all().filter(plan = plan).order_by('financial_institution').filter(maturity_date__year=next_year)
for inv in next_il:
   total_m2 += 0 if inv.maturity_amount is None else inv.maturity_amount

I actually like this better:

next_il = Investment.objects.all().filter(plan = plan).order_by('financial_institution').filter(maturity_date__year=next_year)
for inv in next_il:
   try:
       total_m2 += inv.maturity_amount
   except TypeError:
       log.warning( "Null maturity amount" )