Create two objects in save method

Question

I want to overwrite a save method so that two objects are created for each save instead of one. How would I do the following?

class Message(models.Model):
    thread = models.ForeignKey('MessageThread')
    content = models.CharField(max_length=5000)
    sender = models.ForeignKey(UserProfile, related_name='message_sender')

    # filled in automatically on save()
    timestamp = models.DateTimeField(auto_now_add=True)
    recipient = models.ForeignKey(UserProfile, related_name='message_recipient')
    status = models.CharField(choices=MESSAGE_STATUS, max_length=64, default='unread')

    def save(self, *args, **kwargs):
        """
        When a message is created, this will save TWO objects of it.
        """
        sender = self.sender
        thread_initiator = self.thread.initiator
        thread_recipient = self.thread.recipient
        if sender == thread_recipient:
            self.recipient = thread_initiator
        else:
            self.recipient = thread_recipient
        self.status = 'unread' 
        super(Message, self).save(*args, **kwargs)

        # saving the second object creates an error
        Message.objects.create(thread=self.thread, content=self.content, sender=sender, recipient=sender, status='read')

--> RuntimeError: maximum recursion depth exceeded while calling a Python object

David542 · Accepted Answer · 2012-06-09 22:27:16Z

3

Do two super's, and don't forget to increment the pk if there is an autoincrementing field or an IntegrityError will be raised.

def save(self, *args, **kwargs):
    sender = self.sender
    thread_initiator = self.thread.initiator
    thread_recipient = self.thread.recipient
    if sender == thread_recipient:
        self.recipient = thread_initiator
    else:
        self.recipient = thread_recipient
    self.status = 'unread' 
    super(Message, self).save(*args, **kwargs)

    # instead of Message.objects.create(thread=self.thread, content=self.content, sender=sender, recipient=sender, status='read')
    self.pk +=1
    self.sender = sender
    self.recipient = sender
    self.status = 'read'
    super(Message, self).save(*args, **kwargs)

answered Jun 9, 2012 at 22:27

David542

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1 Comment

tapan Over a year ago

Instead of incrementing the pk, just make it None and let Django assign the pk when save is called.

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