How to put timedelta in django model?

Question

With inspectdb I was able to get a "interval" field from postgres into django. In Django, it was a TextField. The object that I retrieved was indeed a timedelta object!

Now I want to put this timedelta object in a new model. What's the best way to do this? Because putting a timedelta in a TextField results in the str version of the object...

Since Django 1.8 you can use DurationField. – guettli Apr 12 '18 at 09:08 — guettli, Apr 12 '18 at 09:08

score 110 · Answer 1 · edited Feb 14 '19 at 23:53

110

Since Django 1.8 you can use DurationField.

edited Feb 14 '19 at 23:53

SukiCZ

300
5
10

answered Apr 08 '15 at 13:35

Marc Tudurí

1,869
3
18
22

4

SO on how to use: https://stackoverflow.com/questions/30222660/how-should-i-use-durationfield-in-my-model – Csaba Toth Nov 18 '19 at 21:37

score 32 · Accepted Answer · edited Jul 16 '14 at 22:08

32

You can trivially normalize a timedelta to a single floating-point number in days or seconds.

Here's the "Normalize to Days" version.

float(timedelta.days) + float(timedelta.seconds) / float(86400)

You can trivially turn a floating-point number into a timedelta.

>>> datetime.timedelta(2.5)
datetime.timedelta(2, 43200)

So, store your timedelta as a float.

Here's the "Normalize to Seconds" version.

timedelta.days*86400+timedelta.seconds

Here's the reverse (using seconds)

datetime.timedelta( someSeconds/86400 )

edited Jul 16 '14 at 22:08

Johndt

4,187
1
23
29

answered Apr 29 '09 at 11:40

S.Lott

384,516
81
508
779

1

off course you mean float(timedelta.days) + float(timedelta.seconds)/float(86400) ... but it works! – Jack Ha Apr 29 '09 at 11:52
1

@Jack Ha: Thanks for spotting the problem. – S.Lott Apr 29 '09 at 12:08
timedelta.days+timedelta.seconds/86400.0 – aehlke Jan 07 '10 at 02:19
3

Since python 2.7 you can normalize to seconds using the [timedelta.total_seconds](http://docs.python.org/2/library/datetime.html#datetime.timedelta.total_seconds) method. – Lauritz V. Thaulow Jan 17 '13 at 13:25

Garrett Hyde · Answer 3 · 2012-05-14T01:21:15.930

8

First, define your model:

class TimeModel(models.Model):
    time = models.FloatField()

To store a timedelta object:

# td is a timedelta object
TimeModel.objects.create(time=td.total_seconds())

To get the timedelta object out of the database:

# Assume the previously created TimeModel object has an id of 1
td = timedelta(seconds=TimeModel.objects.get(id=1).time)

Note: I'm using Python 2.7 for this example.

edited May 14 '12 at 01:21

answered May 14 '12 at 01:16

Garrett Hyde

5,409
8
49
55

1

on python with version lower than 2.7 can be used formula: `total_seconds = (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / 10**6` – Pol Jun 21 '12 at 14:40
This is great. Thank you for being both concise and thorough – R Claven Mar 27 '15 at 17:02

score 7 · Answer 4 · answered Apr 16 '11 at 12:23

7

https://bitbucket.org/schinckel/django-timedelta-field/src

answered Apr 16 '11 at 12:23

Python

79
1
1

In a repository: check. Works: check. Thanks for sharing. – KobeJohn Oct 04 '11 at 23:34
no longer available, I got a 404 – OMY Jul 09 '22 at 18:45

score 4 · Answer 5 · answered Jun 06 '13 at 05:47

There is a ticket which dates back to July 2006 relating to this: https://code.djangoproject.com/ticket/2443

Several patches were written but the one that was turned in to a project: https://github.com/johnpaulett/django-durationfield

Compared to all the other answers here this project is mature and would have been merged to core except that its inclusion is currently considered to be "bloaty".

Personally, I've just tried a bunch of solutions and this is the one that works beautifully.

from django.db import models
from durationfield.db.models.fields.duration import DurationField

class Event(models.Model):
    start = models.DateTimeField()
    duration = DurationField()

    @property
    def finish(self):
        return self.start + self.duration

Result:

$ evt = Event.objects.create(start=datetime.datetime.now(), duration='1 week')
$ evt.finish
Out[]: datetime.datetime(2013, 6, 13, 5, 29, 29, 404753)

And in admin:

Change event

Duration: 7 days, 0:00:00

It looks like in Django 1.8, that ticket will finally be closed and Django will have a `DurationField`: https://docs.djangoproject.com/en/dev/releases/1.8/#new-data-types — nnyby, Dec 31 '14 at 18:46

score 3 · Answer 6 · answered Jul 25 '10 at 12:16

3

For PostgreSQL, use django-pgsql-interval-field here: http://code.google.com/p/django-pgsql-interval-field/

answered Jul 25 '10 at 12:16

dotz

884
1
8
17

colins44 · Answer 7 · 2015-04-10T13:38:34.177

2

Putting this out there cause it might be another way to solve this problem. first install this library: https://pypi.python.org/pypi/django-timedeltafield

Then:

import timedelta

class ModelWithTimeDelta(models.Model):
    timedeltafield = timedelta.fields.TimedeltaField()

within the admin you will be asked to enter data into the field with the following format: 3 days, 4 hours, 2 minutes

edited Apr 10 '15 at 13:38

answered Mar 03 '15 at 11:03

colins44

544
6
9

I prefer this solution with Django 1.7 because it's in the pip repo and not an external source. – Joseph Coco Nov 18 '15 at 23:16

score 0 · Answer 8 · answered Jan 07 '21 at 07:41

There is a workaround explained here. If you're using Postgresql, then multiplying the result of F expression with timedelta solves the problem. For example if you have a start_time and a duration in minutes, you can calculate the end_time like this:

YourModel.objects.annotate(
    end_time=ExpressionWrapper(F('start_time') + timedelta(minutes=1) * F('duration'), output_field=DateTimeField())
)

How to put timedelta in django model?

8 Answers8

Linked

Related