如何在当前年份，django中查询当前年份的对象

Question

I need to find total objects created in

1. current year
2. current month
3. last month
4. last year

I am thinking like this

    this_year = datetime.now().year
    last_year = datetime.now().year -1
    this_month = datetime.now().month
    last month = (datetime.today() - timedelta(days=30)).month

Use like

Order.objects.filter(created_at__month=this_month)

The problem is

1. last_month i want is calendar month not 30 days back
2. i am not sure whether created_at__month=this_month will match current month or same month in previous year
3. is it possible to get all counts in single query

Answer 1

today = datetime.datetime.now()

1 Current year

Order.objects.filter(created_at__year=today.year)

2 Current month

Order.objects.filter(created_at__year=today.year, created_at__month=today.month)

3 Last month

last_month = today.month - 1 if today.month>1 else 12
last_month_year = today.year if today.month > last_month else today.year - 1

Order.objects.filter(created_at__year=last_month_year, created_at__month=last_month)

4 Last year

last_year = today.year - 1
Order.objects.filter(created_at__year=last_year)

5 Single Query

As last year + current year includes last month and current month, and all orders>= last_year includes current year, the query is super simple:

Order.objects.filter(created_at__year__gte=last_year)

Answer 2

If you want it in separate queries, do something like that.

from_this_year = Order.objects.filter(created_at__year=this_year)
from_last_year = Order.objects.filter(created_at__year=last_year)
from_june = Order.objects.filter(created_at__month='06',created_at__year=this_year)
from_this_month = Order.objects.filter(created_at__month=this_month,created_at__year=this.year)

note: in my example, I put '06' that is June, but you can change it.

Answer 3

I don't think you'll be able to just match the "month" or "year" part of a date field without some significant fiddling or annotating. Most likely, your simplest solution is to define the start and end of the range you want and search against that. And that might involve a little bit of work.

For example, last calendar month would be:

today = datetime.now()
if today.month == 1:
    last_month_start = datetime.date(today.year-1, 12, 1)
    last_month_end = datetime.date(today.year-1, 12, 31)
else:
    last_month_start = datetime.date(today.year, today.month -1, 1)
    last_month_end = datetime.date(today.year, today.month, 1) - datetime.timedelta(days=1)
Order.objects.filter(created_at__gte=last_month_start, created_at__lte=last_month_end)

GTE and LTE are "greater than or equal" and "less than or equal". Also worth noting, we use timedelta to figure out what the day before the first of this month is rather than go through all the different cases of whether the previous month had 28, 29, 30 or 31 days.