Example for Python thread

example_python_thread_with_django.py

models.py

class PurchaseOrder(models.Model):
    total_value = models.DecimalField(max_digits=12, decimal_places=2, null=True, blank=True)

def purchase_order_post_save_handler(sender, instance, **kwargs):
    project_po_value_update_thread = accounting.threads.ProjectPoValueUpdateThread(instance)
    project_po_value_update_thread.start() 

post_save.connect(purchase_order_post_save_handler, sender=PurchaseOrder)


threads.py

class ProjectPoValueUpdateThread(threading.Thread):
    """
    thread to update the po.project with the latest po values
    called via the save method of the purchase order
    """

    def __init__(self, purchase_order):
        self.purchase_order = purchase_order
        threading.Thread.__init__(self)

    def run(self):
        "starts the thread to update project po values"
        try:
            project = self.purchase_order.project
            #update active po budget
            active_po_sum = PurchaseOrder.objects.filter(project=project, is_active=True).aggregate(total_value_sum=Sum('total_value'))
            active_total_value_sum = active_po_sum['total_value_sum']
            project.total_value = active_total_value_sum
            project.save()