Re: How to aggregate values by month

Personally I hate writing raw SQL so I would probably try something
like this (untested):

sales = Sale.objects.filter(date_created__range=(init_date,ends_date))
.values(date_ created__month)
.aggregate(total_sales=Sum('total_value'))

sales_by_month = [(x.year, x.month, [y for y in sales if y.year ==
x.year and y.month == x.month])
for x in set([z.year, z.month for z in sales])]

Should give you a list of (year, month, subqueryset) tuples. Of
course, there might be performance issues with nested list
comprehensions like that depending on the size of the initial
queryset, but at least it's a one-line, SQL-free solution!

On Oct 28, 9:31 am, Rogério Carrasqueira
<rogerio.carrasque...@gmail.com> wrote:
> Hello!
>
> I'm having an issue to make complex queries in django. My problem is, I have
> a model where I have the sales and I need to make a report showing the sales
> amount per month, by the way I made this query:
>
> init_date = datetime.date(datetime.now()-timedelta(days=365))
> ends_date = datetime.date(datetime.now())
> sales =
> Sale.objects.filter(date_created__range=(init_date,ends_date)).values(date_ created__month).aggregate(total_sales=Sum('total_value'))
>
> At the first line I get the today's date past one year
> after this I got the today date
>
> at sales I'm trying to between a range get the sales amount grouped by
> month, but unfortunatelly I was unhappy on this, because this error
> appeared:
>
> global name 'date_created__month' is not defined
>
> At date_created is the field where I store the information about when the
> sale was done., the __moth was a tentative to group by this by month.
>
> So, my question: how to do that thing without using a raw sql query and not
> touching on database independence?
>
> Thanks so much!
>
> Rogério Carrasqueira
>
> ---
> e-mail: rogerio.carrasque...@gmail.com
> skype: rgcarrasqueira
> MSN: rcarrasque...@hotmail.com
> ICQ: 50525616
> Tel.: (11) 7805-0074

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