Execute code on model creation in Django

Question

I want to execute some code in a Django model when it is first created. After that whenever it is saved I want to execute some other code. The second task can be easily done by overriding the save() method. How can I do the first task?

Answer 1

Extending sdolan's answer by using receiver decorator:

from django.db import models
from django.dispatch import receiver

class MyModel(models.Model):
    pass

@receiver(models.signals.post_save, sender=MyModel)
def execute_after_save(sender, instance, created, *args, **kwargs):
    if created:
        # code

Answer 2

You can use django signals' post_save:

# models.py

from django.db.models import signals

class MyModel(models.Model):
    pass

def my_model_post_save(sender, instance, created, *args, **kwargs):
    """Argument explanation:

       sender - The model class. (MyModel)
       instance - The actual instance being saved.
       created - Boolean; True if a new record was created.

       *args, **kwargs - Capture the unneeded `raw` and `using`(1.3) arguments.
    """
    if created:
        # your code goes here


# django 1.3+
from django.dispatch import dispatcher
dispatcher.connect(my_model_post_save, signal=signals.post_save, sender=MyModel)

# django <1.3
from django.db.models.signals import post_save
post_save.connect(my_model_post_save, sender=MyModel)