custom save method on model - django

问题

I am overriding the save method on one of my models:

def save(self, *args, **kwargs):
    self.set_coords()
    super(Post, self).save(*args, **kwargs)

def __unicode__(self):
    return self.address

# set coordinates
def set_coords(self):
    toFind = self.address + ', ' + self.city + ', ' + \
        self.province + ', ' + self.postal

    (place, location) = g.geocode(toFind)

    self.lat = location[0]
    self.lng = location[1]

However, I only want to run set_coords() once, when the post is being created. This function should not run when the model is being updated.

How can I accomplish this? Is there any way of detecting if the model is being created or updated?

回答1:

def save(self, *args, **kwargs):
    if not self.pk:
        self.set_coords()
    super(Post, self).save(*args, **kwargs)

回答2:

I think the correct way to do it is using post_save signal:

def set_coords(sender, **kw):
    model_instance = kw["instance"]
    if kw["created"]:
        toFind = model_instance.address + ', ' + model_instance.city + ', ' + \
        model_instance.province + ', ' + model_instance.postal
        (place, location) = g.geocode(toFind)
        model_instance.lat = location[0]
        model_instance.lng = location[1]
        model_instance.save()
post_save.connect(set_coords, sender=MyModel)

来源：https://stackoverflow.com/questions/11456913/custom-save-method-on-model-django