Safe concurrent saves for Django models

gistfile1.py

"""
With Django models, calling save() can have undesired consequences, 
particularly in a concurrent environment such a Celery, where model 
instances may be serialized across a message queue. The save() method 
will write all fields to the database which may have already been 
written to by another process or thread, and as such will override 
fields incorrectly.

The mixin below can be used to safely update model instances without 
overriding fields of no concern that may have been written to since 
the object was instantiated.

Usage: 

class SomeModel(UpdateMixin, models.Model):
    # stuff

object.update(slug="myslug")

or

object.slug = "myslug"
object.update("slug")


"""

class UpdateMixin(object):

    def update(self, *args, **kwargs):
        for arg in args:
            kwargs[arg] = getattr(self, arg)
        self.__class__.objects.filter(id=self.id).update(**kwargs)