Matching query doesn't exist after a new object save in Django Admin and sent to Celery task

Question

I'm saving an object in Django Admin (Django 1.8) and passing them to Celery Task. Unfortunately, I got an error [sometimes!]: "Matching query doesn't exist". I know that this is a problem with transaction, but what is the best way to solve that problem?

class MyModelAdmin(admin.ModelAdmin)
    def save_model(self, request, obj, form, change):
        super(MyAdmin, self).save_model(request, obj, form, change)
        if not change:
            celery_task.delay(obj.pk)

@app.task()
def celery_task(obj_pk):
    MyModel.objects.get(pk=obj_pk)

The problem is that a whole view in Django Admin is in transaction.atomic() block. And sometimes celery runs faster that the end of transaction. I'm wondering what is the best way to get this around. Adding an eta while calling celery_task is some creepy idea I think (or maybe not?) - celery_task.apply_async((obj.pk,), eta=+10 seconds)

Answer 1

If someone still looking for this one: Django docs

from django.db import transaction


class MyModelAdmin(admin.ModelAdmin)
    def save_model(self, request, obj, form, change):
        super().save_model(request, obj, form, change)
        if not change:
            transaction.on_commit(lambda: celery_task.delay(obj.pk))

...
@app.task()
def celery_task(obj_pk):
    MyModel.objects.get(pk=obj_pk)