Getting all items less than a month old

Do this:

from datetime import datetime, timedelta

def is_leap_year(year): 
    if year % 100 == 0:
        return year % 100 == 0

    return year % 4 == 0

def get_lapse():
    last_month = datetime.today().month
    current_year = datetime.today().year

    #is last month a month with 30 days?
    if last_month in [9, 4, 6, 11]:
        lapse = 30

    #is last month a month with 31 days?
    elif last_month in [1, 3, 5, 7, 8, 10, 12]:
        lapse = 31

    #is last month February?
    else:
        if is_leap_year(current_year):
            lapse = 29
        else:
            lapse = 30

    return lapse

last_month_filter = datetime.today() - timedelta(days=get_lapse())

items = Item.objects.filter(date_created__gte=last_month_filter)

This will cater for all cases I can think of.

items = Item.objects.filter(created_date__gte=aMonthAgo)

Where aMonthAgo would be calculated by datetime and timedelta.

What is your definition of a "month"? 30 days? 31 days? Past that, this should do it:

from datetime import datetime, timedelta
last_month = datetime.today() - timedelta(days=30)
items = Item.objects.filter(my_date__gte=last_month).order_by(...)

Takes advantange of the gte field lookup.