sum() list from SQLAlchemy output

[Personne]

Hello guys,

I'm sure it is simple. Have a SQLAlchemy query such as:

qp = db.session.query(UInventory, func.sum(UInventory.quantity).label('total')).filter(
            UInventory.location_id == s.loc_id, UInventory.userid == current_user.userid).group_by(UInventory.part_id). subq.all()

Later in my code, I want to sum up the result of the 'total' from the query.

for now I'm using this code, which works well, but I'd like to use sum() function instead:

sum = 0
for q in qp:
    sum += q.total

the type of the variable q is <class 'sqlalchemy.engine.row.Row'>

I tried

max_total = sum(q.total) 

but of course I got this error:

Error:
print(sum(qp.total))
AttributeError: 'list' object has no attribute 'total'

How can I achieve something that simple ?

Thank you

Note: I do not want a SQL query solution !

[Personne]

If have done a bit a research, I found this way, but the performance is quite bad, and I'm still using a loop.

        list = range(10000000)
        starttime = timeit.default_timer()
        for i in list:
            sum1 = 0
            for q in qp:
                sum1 += q.total
        print({timeit.default_timer() - starttime})

        starttime = timeit.default_timer()
        for i in list:
            sum2 = sum([int(q.total) for q in qp])
        print({timeit.default_timer() - starttime})

The sum() is about 2 times slower

[bowlofred]

Note: I do not want a SQL query solution !

Why do you want it to be fast but don't want it to be on the SQL side? Python has lots of good attributes, but speedy loops is not one of them.

[Personne]

Note: I do not want a SQL query solution !

Why do you want it to be fast but don't want it to be on the SQL side? Python has lots of good attributes, but speedy loops is not one of them.

For the simple reason that I know how to do it in SQL ! and I'm trying to understand how Python can do something that simple quickly.

[bowlofred]

Python can't do it as fast. The simple way would be to import func from sqlalchemy and call func.sum() on the query.

sum() will be the fastest way to do it in python, but constructing the container for sum() to operate on may take longer if the query doesn't just hand over those specific values.

[Personne]

Python can't do it as fast. The simple way would be to import func from sqlalchemy and call func.sum() on the query.

sum() will be the fastest way to do it in python, but constructing the container for sum() to operate on may take longer if the query doesn't just hand over those specific values.

I did a quick benchmark, surprisingly the loop is faster than the SQL query.

Anyway thank for your help.