README.md

django-celery-transactions

django-celery-transactions holds on to Celery tasks until the current database transaction is committed, avoiding potential race conditions as described in Celery's user guide. Send tasks from signal handlers without fear!

Features

• If the transaction is rolled back, the tasks are discarded. Django's transaction middleware does this if an exception is raised.
• If transactions aren't being managed, tasks are sent as normal. This means that sending tasks from within Django's shell will work as expected, as will the various transaction decorators commit_manually, commit_on_success, etc.

Installation & Use

1. Install django-celery-transactions from PyPI:

    $ pip install django-celery-transactions
   

2. Use the patched decorator to create your tasks:

    from djcelery_transactions import task
    from models import Model
   
   
    @task
    def print_model(model_pk):
        print Model.objects.get(pk=model_pk)
   

3. Then use them as normal:

    from django.db import transaction
    from models import Model
    from tasks import print_model
   
   
    # This task will be sent after the transaction is committed. This works
    # from anywhere in the managed transaction block (e.g. signal handlers).
    def view(request):
        model = Model.objects.create(...)
        print_model.delay(model.pk)
   
   
    # This task will not be sent (it is discarded) as the transaction
    # middleware rolls the transaction back when it catches the exception.
    def failing_view(request, model_pk):
        print_model.delay(model_pk)
        raise Exception()
   
   
    # This task will be sent immediately as transactions aren't being
    # managed and it is assumed that the author knows what they're doing.
    @transaction.commit_manually
    def manual_view(request, model_pk):
        print_model.delay(model_pk)
        transaction.commit()