Question

The Django docs only list examples for overriding save() and delete(). However, I’d like to define some extra processing for my models only when they are created. For anyone familiar with Rails, it would be the equivalent to creating a :before_create filter. Is this possible?

Answer 1

Overriding __init__() would cause code to be executed whenever the python representation of object is instantiated. I don’t know rails, but a :before_created filter sounds to me like it’s code to be executed when the object is created in the database. If you want to execute code when a new object is created in the database, you should override save(), checking if the object has a pk attribute or not. The code would look something like this:

def save(self, *args, **kwargs):
    if not self.pk:
        # This code only happens if the objects is
        # not in the database yet. Otherwise it would
        # have pk
    super(MyModel, self).save(*args, **kwargs)