Any way to force Django to commit a write so another process can read the correct data from DB?

[Stodge]

My website uses a combination of Django + Java apps to function. For this particular problem, a record is deleted from the DB via a TastyPie resource DELETE operation. A Django signal post_delete handleris invoked, which submits a DELETE request to Jetty running in the Java app. The Java app then performs a query using Hibernate.

What appears to be happening is that Django thinks the record was deleted:

DynamicVolume.objects.filter(user=instance.user).count()

Returns ZERO.

However, the Java app thinks the record still exists unless I make it sleep for several seconds before asking Hibernate to query the DB.

I've tried forcing Hibernate to clear its cache with no success. Is there a way to force Django to commit the deletion (flush the cache)?

Thanks

[Constantine Covtushenko]

Hi Stodge,

As said in Django current version of documentation, 'post_delete' signal is sent after record is deleted. This means also that transaction is closed at that moment. And DB should not has deleted instance any more.

I have double checked the Django code and can say that Django send that signal just before transaction is committed.

So technically instance should be inside DB for Hibernate processing.

I can suggest you to create a custom signal and send it after transaction closed.

That should solve your problem.

Regards,

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[Luis Zárate]

I thing java apps have a cache and it is java who is not looking in the database.  I was a similar problem with hirbernate time ago. But I never solved other person solved it and I don't know how.

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[Mike Dewhirst]

On 28/07/2016 5:46 AM, Constantine Covtushenko wrote:
> Hi Stodge,
>

> As said in Django current version of documentation
> <https://docs.djangoproject.com/en/1.9/ref/signals/#post-delete>,

> 'post_delete' signal is sent after record is deleted. This means also
> that transaction is closed at that moment. And DB should not has deleted
> instance any more.
>
> I have double checked the Django code and can say that Django send that
> signal just before transaction is committed.

Is this a Django bug?

Is it the same for post_save?

Mike

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[Constantine Covtushenko]

Hi Mike,

It is not a bug.

It is just how it works.

Regards

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