django-concurrency is a optimistic locking library for Django 1.4. It works adding a VersionField to the model, each time a model is successfully saved the VersionNumber is incremented.

sample code:

from concurrency.fields import IntegerVersionField

class ConcurrentModel( models.Model ):
    version = IntegerVersionField( )

Now if if you try:

a = ConcurrentModel.objects.get(pk=1)
b = ConcurrentModel.objects.get(pk=1)
a.save()
b.save()

you will get a RecordModifedError on b.save()

• Project home page: https://github.com/saxix/django-concurrency
• Issue tracker: https://github.com/saxix/django-concurrency/issues?sort
• Download: http://pypi.python.org/pypi/django-concurrency/
• Docs: http://readthedocs.org/docs/django-concurrency/en/latest/