Create model instance using data from related object

Question

I have two following models (with OneToOne relation):

class Company(BaseModel):
    name = models.CharField(max_length=64)
    address_street = models.CharField(max_length=64)
    address_city = models.CharField(max_length=64)
    address_zipcode = models.CharField(max_length=6)
    # ...many other fields here...

class InvoicingData(BaseModel):
    company = models.OneToOneField(Company, null=True, blank=True)
    company_name = models.CharField(max_length=64)
    address_street = models.CharField(max_length=64)
    address_city = models.CharField(max_length=64)
    address_zipcode = models.CharField(max_length=6)

I want to auto-create InvoicingData model instance, when new Company is being added. I wanted to use signal to do so:

@receiver(post_save, sender=Company)
def create_invoicing_data(sender, instance, created, **kwargs):
    if created:
        # WHAT HERE?

Is there any simple, automated way to copy shared fields values from one model to another?

catavaran · Accepted Answer · 2015-02-16 09:35:57Z

2

You can use Model._meta to get the list of the field names:

@receiver(post_save, sender=Company)
def create_invoicing_data(sender, instance, created, **kwargs):
    if created:

        invoice_fields = InvoicingData._meta.get_all_field_names()

        data = dict((field_name, getattr(instance, field_name))
                       for field_name in Company._meta.get_all_field_names()
                       if field_name != 'id' and field_name in invoice_fields)

        InvoicingData.objects.create(company=instance,
                                     company_name=instance.name,
                                     **data)

answered Feb 16, 2015 at 9:35

catavaran

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Mark R. · Accepted Answer · 2015-02-16 09:34:19Z

1

@receiver(post_save, sender=Company)
def create_invoicing_data(sender, instance, created, **kwargs):
    if created:
        invdata = InvoicingData(company=instance)
        # set any other fields on invdata if desired
        invdata.save()

answered Feb 16, 2015 at 9:34

Mark R.

1,3238 silver badges14 bronze badges

3 Comments

dease Over a year ago

I also need to copy all other fields (address, etc)

Mark R. Over a year ago

You could use @catavaran's answer below, or simply set the fields manually, E.G., invdata.address_city = instance.address_city, etc.

dease Over a year ago

In my case that seems to be a simpler solution. Thanks!

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