correctly aggregating model objects and simple view calculation - django

Question

if "allotted_pto" (paid time off) is an integer field (expressing number of days) in a UserProfile model:
class UserProfile(models.Model):
user = models.ForeignKey(User, unique=True)
fullname = models.CharField(max_length=64, unique=False)
company = models.CharField(max_length=50, choices=CLIENT_CHOICES)
...
allotted_pto = models.IntegerField(max_length=2, blank=True, null=True)
...
User.profile = property(lambda u: UserProfile.objects.get_or_create(user=u)[0])
and "total_days" returns an integer from a vacation request model:
class LeaveRequest(models.Model):
employee = models.ForeignKey(UserProfile)
supervisor = models.ForeignKey(UserProfile, related_name='+', blank=False, null=False)
...
total_days = models.IntegerField(max_length=2, blank=True, null=True)
def __unicode__ (self):
return u'%s %s' % (self.employee, self.submit_date)
def save(self, *args, **kwargs):
fromdate = self.start_date
todate = self.return_date
daygenerator = (fromdate + timedelta(x + 1) for x in xrange((todate - fromdate).days))
self.total_days = sum(1 for day in daygenerator if day.weekday() < 5)
super(LeaveRequest, self).save(*args, **kwargs)
...
how can I construct a view that gives me the sum of "total_days" from a filter set of records and subtract that sum from the "allotted_pto" in the user profile? The simple view I wrote (see below) produces the number of "total_days" objects (in dictionary form) as opposed to counting the actual days, and the request for "allotted_pto" is apparently incorrectly constructed because it returns nothing at all...
#views.py
def leave_screen(request, id):
profile = UserProfile.objects.get(user=id)
records = LeaveRequest.objects.filter(employee=id)
agg_pto = LeaveRequest.objects.aggregate(Count('total_days'))
if profile.allotted_pto: #if the allotted_pto field in UserProfile is not empty
allotted_pto = profile.allotted_pto
remaining_pto = allotted_pto - agg_pto
else:
remaining_pto = "na"
return render_to_response("vacation/leave_request.html", {'records': records, 'agg_pto': agg_pto, 'remaining_pto': remaining_pto})
ok, figured out calculation:
def leave_screen(request, id):
...
agg_pto = LeaveRequest.objects.filter(employee=id).aggregate(Sum('total_days'))
agg_pto = agg_pto['total_days__sum']
just have to figure out how to pull the allotted_pto integer from the User Profile model.

Answer 1

ok, so this wasn't as difficult as I thought. The first challenge was to get an aggregate sum of objects. My first attempt was close but I should have just used "Sum" as opposed to "Count":
agg_pto = LeaveRequest.objects.filter(employee=id).aggregate(Sum('total_days'))
then I just used the python method for extracting the value from a dictionary:
agg_pto = agg_pto['total_days__sum']
finally:
def leave_screen(request, id):
user = request.user.id
profile = request.user.get_profile()
records = LeaveRequest.objects.filter(employee=id).order_by('-submit_date')
agg_pto = LeaveRequest.objects.filter(employee=id).aggregate(Sum('total_days'))
agg_pto = agg_pto['total_days__sum']
allotted_pto = profile.allotted_pto
if allotted_pto: #if the allotted_pto field in UserProfile is not empty
remaining_pto = allotted_pto - agg_pto
else:
remaining_pto = "na"
supervised_records = LeaveRequest.objects.filter(supervisor=id).order_by('-submit_date')
return render_to_response("vacation/leave_request.html", {'records': records, 'supervised_records': supervised_records, 'agg_pto': agg_pto, 'allotted_pto': allotted_pto, 'remaining_pto': remaining_pto, 'profile': profile })
I don't know why it was so hard for me to figure out the syntax for pulling objects from the UserProfile. But I do know that the django-debug-toolbar is very helpful.