Django - update dictionary with missing date values, set to 0 - django

Question

So to display a small bargraph using Django and Chart.js I constructed the following query on my model.
views.py
class BookingsView(TemplateView):
template_name = 'orders/bookings.html'
def get_context_data(self, **kwargs):
today = datetime.date.today()
seven_days = today + datetime.timedelta(days=7)
bookings = dict(Booking.objects.filter(start_date__range = [today, seven_days]) \
.order_by('start_date') \
.values_list('start_date') \
.annotate(Count('id')))
# Edit set default for missing dictonairy values
for dt in range(7):
bookings.setdefault(today+datetime.timedelta(dt), 0)
# Edit reorder the dictionary before using it in a template
context['bookings'] = OrderedDict(sorted(bookings.items()))
This led me to the following result;
# Edit; after setting the default on the dictionary and the reorder
{
datetime.date(2019, 8, 6): 12,
datetime.date(2019, 8, 7): 12,
datetime.date(2019, 8, 8): 0,
datetime.date(2019, 8, 9): 4,
datetime.date(2019, 8, 10): 7,
datetime.date(2019, 8, 11): 0,
datetime.date(2019, 8, 12): 7
}
To use the data in a chart I would like to add the missing start_dates into the dictionary but I'm not entirely sure how to do this.
So I want to update the dictionary with a value "0" for the 8th and 11th of August.
I tried to add the for statement but I got the error;
"'datetime.date' object is not iterable"

Answer 1

Like the error says, you can not iterate over a date object, so for start_date in seven_days will not work.
You can however use a for loop here like:
for dt in range(7):
bookings.setdefault(today+datetime.timedelta(dt), 0)
A dictionary has a .setdefault(..) function that allows you to set a value, given the key does not yet exists in the dicionary. This is thus shorter and more efficient than first checking if the key exists yourself since Python does not have to perform two lookups.
EDIT: Since python-3.7 dictionaries are ordered in insertion order (in the CPython version of python-3.6 that was already the case, but seen as an "implementation detail"). Since python-3.7, you can thus sort the dictionaries with:
bookings = dict(sorted(bookings.items()))
Prior to python-3.7, you can use an OrderedDict [Python-doc]:
from collections import OrderedDict
bookings = OrderedDict(sorted(bookings.items()))