Django query formatting datetime output

Question

My Django install uses a PostgreSQL backend.

I am doing the following in a Django view:

completedItems = Completed.objects.filter(user_id=1)
return HttpResponse(completedItems.values('item_id','item_name','event_datetime','item_id__item_name'))

For the date timefield, this returns:

'event_datetime': datetime.datetime(2014, 6, 4, 0, 49, 38, tzinfo=<UTC>)

I am trying to serialize the return using json.dumps, and this formatting is giving me grief. What is the best way to reformat the datetime return from the query so I can serialize it properly?

I tried to use:

datetime.strptime('event_datetime',"datetime.datetime(%Y, %m, %d, %H, %M, %S, tzinfo=<%Z>)")

but it complains that the date does not match the format string.

I don't understand what you are trying to do. strptime is for converting a string to a datetime, but you seem to have a datetime already. — Daniel Roseman
– Daniel Roseman, Commented Jun 14, 2014 at 20:25
Ahh, sorry. I left out an important detail. I'm trying to convert the datetime into a string that I can serialize and pass to another app in JSON (this Django app is essentially serving as a REST server). I'm looking for a good way to get a seralizable string from a datetime. — itnAAnti
– itnAAnti, Commented Jun 15, 2014 at 13:32

Dmytro Ivashchenko · Accepted Answer · 2020-04-29 14:40:23Z

8

For use "to_char" function PostgreSQL in some queryset possibly via annotate with Func, (from Django 1.8)

rows = some_queryset.annotate(str_date=Func(F('date'), Value('DD.MM.YYYY'), function='to_char'))

then each item in rows has 'str_date' as string date in format 'DD.MM.YYYY'

from django.db.models import Func, F, Value
'date' in F('date') is field of Model with datetime data

answered Apr 29, 2020 at 14:40

Dmytro Ivashchenko

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Community · Accepted Answer · 2017-05-23 11:49:34Z

0

I ended up using .extra to inject PostgreSQL "to_char" to re-format this. This is the solution suggested by PKKid here.

edited May 23, 2017 at 11:49

CommunityBot

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answered Jun 15, 2014 at 15:13

itnAAnti

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