Document auto_now behavior with QuerySet.update()

[Ahmed Saidi]

I don't know if this is a bug or not, but when using update(), the DateTime fields with auto_now are not updated to the current time. The documentation of auto_now doesn't say anything about that situation.
For example:

#  This won't update `updated_at`:
Order.objects.filter(user_id=7).update(check_count=3)

# You have to explicitly include it in update()
Order.objects.filter(user_id=7).update(check_count=3, updated_at=timezone.now())

[AMaini503]

I will try to work on this. But should update be modified to include timestamp by itself or documentation should be altered to state that timestamp needs to be passed explicitly ?

[honsdomi]

Hello, can someone confirm if this requires modifying code or just documentation?

[Ahmed Saidi]

Hi, Sorry for delay in replay.
I think documentation change is better, so existing applications won't have to do any changes to upgrade.
As i understand now, you must call save() for the auto-update field to be populated, which is fine, but explicitly mentioning that in the documentation good for new users (like me).
Thank you.

[Duane Hilton]

Replying to boussouira:
I think the documentation already specifies this: "Automatically set the field to now every time the object is saved."
​https://docs.djangoproject.com/en/1.9/ref/models/fields/#django.db.models.DateField.auto_now

Does the documentation need something more?

[Ahmed Saidi]

I think that is good enough.
Thank you

[Tim Graham]

How about adding something like, "The field is not updated when using QuerySet.update() to update other fields."

[Duane Hilton]

Okay, I added a note to that effect. ​https://github.com/django/django/pull/6281

[Tim Graham <timograham@…>]

In ca5c05d:

Fixed #26239 -- Added a note about how auto_now works with QuerySet.update().

[Tim Graham <timograham@…>]

In 421ad283:

[1.9.x] Fixed #26239 -- Added a note about how auto_now works with QuerySet.update().

Backport of ca5c05ddbe91f4aae38c4543240dbda5f1fb1db2 from master