Running total with annotated querysets in Django

Question

I have a running total template tag which looks like

from django.template import Library 

register = Library() 

@register.filter
def running_total(list, var_name):
    return sum(getattr(obj, var_name) or 0 for obj in list)

It works when I need a running total in normal querysets, but when I use a annotated queryset I get the exception 'dict' object has no attribute 'total'.

When I print a normal queryset in my template I get [<Item: Item #1>], but when I print a annotated queryset I get a list with a tuple [{'total_amount': Decimal('0.00'), ...].

Should I somehow convert the list in my templatetag?

I've tried adding

list = list(list)

but it still doesn't work.

use a better name than list. you are overriding the default type. — karthikr
– karthikr, Commented Sep 2, 2014 at 13:53

Andrey Nelubin · Accepted Answer · 2014-09-02 13:50:48Z

1

arr = []
for obj in list:
    if isinstance(obj, dict):
        arr.append(obj[var_name] if var_name in obj else 0)
    else:
        arr.append(getattr(obj, var_name) or 0)
return sum(arr)

The reason is that elements in annotated queryset is not model instance anymore, it's dict.

answered Sep 2, 2014 at 13:50

Andrey Nelubin

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