Django create instance of model from another models save method

Question

I have an Article model which has a OnetoOne relationship with a Catalog Model. Is it possible to create an instance of Catalog from within the save method of the Article. I'd like to attach an Article with a Catalog of the same name, it would be easiest to create these at the same time.

Here is my Catalog class:

class Catalog(models.Model):
    name = models.CharField(max_length=100)
    price = models.IntegerField

    def __unicode__(self):
        return self.name

Article Class:

class Article(models.Model):
  catalog = models.OneToOneField(Catalog, related_name='article_products', blank=True, null=True)
  title = models.CharField(max_length=200)
  abstract = models.TextField(max_length=1000, blank=True)
  full_text = models.TextField(blank=True)
  proquest_link = models.CharField(max_length=200, blank=True, null=True)
  ebsco_link = models.CharField(max_length=200, blank=True, null=True)

  def __unicode__(self):
      return unicode(self.title)


  def save(self, *args, **kwargs):
      self.full_text = self.title
      super(Article, self).save(*args, **kwargs)

I'd like to some logic similar to this within the save method: I'm not sure if it's possible though

cat = Catalog.create(title = self.title)
      cat.save()

karthikr · Accepted Answer · 2014-11-01 00:48:21Z

5

You could instead use post_save signal for creating catalog objects at the time of creation of article objects. This would ensure creation of the catalog objects, without having to include non-relevant code in the article models' save method.

from django.db.models.signals import post_save

# method for updating
def create_catalog(sender, instance, created, **kwargs):
     if instance and created: 
         #create article object, and associate


post_save.connect(create_catalog, sender=Article)

answered Nov 1, 2014 at 0:48

karthikr

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2 Comments

byrdr Over a year ago

I used a slightly different method but this got me on the right track. Thanks @receiver(post_save, sender=Article) def create_catalog(sender, **kwargs): if kwargs.get('created', False): Catalog.objects.get_or_create(name=kwargs.get('instance'), price='10')

rowman Over a year ago

The comment inside the code shouldn't read # create catalog object, and associate?

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