How to subtract current date with date from database

Question

I have a Donor table with lastAttendance column. How can I subtract current day with selected lastAttendance date?

d0 = Donor.objects.only("lastAttendance")
d1 = datetime.now()
delta = d1 - d0

Error:

unsupported operand type(s) for -: 'datetime.datetime' and 'QuerySet'

d0 is a queryset, ie a container of all your Donor objects with their lastAttendance fields. Which one do you want to calculate the date for? — Daniel Roseman, Jun 19 '17 at 11:21
How did that in any way answer my question? You have *multiple* Donor objects, each with their own lastAttendance value. Which do you want to calculate? — Daniel Roseman, Jun 19 '17 at 11:30
Isnt that a duplicate of : https://stackoverflow.com/questions/2861770/how-do-i-subtract-two-dates-in-django-python — mbieren, Jun 19 '17 at 13:11

Arun · Answer 1 · 2017-06-19T11:20:17.587

0

Try the following code

from django.utils import timezone  
d0 = Donor.objects.only("lastAttendance")[0]
d1 = timezone.now()
delta = d1 - d0.lastAttendance

edited Jun 19 '17 at 11:20

answered Jun 19 '17 at 11:04

Arun

still the same error: unsupported operand type(s) for -: 'datetime.datetime' and 'QuerySet' – kasia Jun 19 '17 at 11:07
@kasia `Donor.objects.only("lastAttendance")` returns a queryset. In order to get results, you should iterate through the list. Also please note the update. – Arun Jun 19 '17 at 11:24
@kasia: If you want to iterate the difference in a template, you can iterate through the objects, then store the difference in a list. In the template, you can use a for loop to display the values. – Arun Jun 19 '17 at 11:44

score 0 · Accepted Answer · answered Jun 19 '17 at 11:07

0

answered Jun 19 '17 at 11:07

hansTheFranz

2 Answers2