Cannot assign must be a instance

Using Django Mystery Errors
1

I’ve run into a problem that I just can’t figure out. I hope someone can help. I have the following models and I’m simply trying to create a one-to-one object and save it, but I get the following error.
ValueError: Cannot assign "(<OrderBox: testsku>,)": "Shipping.order_box" must be a "OrderBox" instance.

Models.py

class OrderBox(models.Model):
	order = models.ForeignKey(Order, related_name='order_boxes', on_delete=models.CASCADE)
	sku = models.CharField(max_length=10)
	name = models.CharField(max_length=100)
	length = models.PositiveSmallIntegerField(default=1)
	width = models.PositiveSmallIntegerField(default=1)
	height = models.PositiveSmallIntegerField(default=1)
	index = models.PositiveSmallIntegerField(default=1)

	def __str__(self):
		return self.sku

class Shipping(models.Model):
	order_box = models.OneToOneField(OrderBox, related_name='shipping_order', on_delete=models.CASCADE)
	order_no = models.CharField(max_length=20)
	order_id = models.CharField(max_length=20)
	order_key = models.CharField(max_length=50)
	ship_date = models.DateField()

	def __str__(self):
		return self.order_no

But when I run the following code in my views file I get the error below. But I’m clearly supplying it an OrderBox instance.

def generate_shipping_label(request, order_pk):
	ob = OrderBox(
		order = Order.objects.get(pk=order_pk),
		sku = "testsku",
		name = "testname"
	)
	ob.save()

	print(ob.pk, type(ob))
	shipping = Shipping()
	shipping.order_box = ob,
	shipping.order_no = "12345",
	shipping.order_id = "2",
	shipping.order_key = "3",
	shipping.ship_date = date.today() + timedelta(days=1)
	
	shipping.save()

Traceback

40 <class 'orders.models.OrderBox'>
Internal Server Error: /orders/shipping-label/22515
Traceback (most recent call last):
  File "c:\Users\antho\Documents\Business\Projects\Django Projects\mms_env\lib\site-packages\django\core\handlers\exception.py", line 55, in inner
    response = get_response(request)
  File "c:\Users\antho\Documents\Business\Projects\Django Projects\mms_env\lib\site-packages\django\core\handlers\base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "C:\Program Files\Python310\lib\contextlib.py", line 79, in inner
    return func(*args, **kwds)
  File "C:\Users\antho\Documents\Business\Projects\Django Projects\MMS\mms-master-data\orders\views\order_processing.py", line 852, in generate_shipping_label
    shipping.order_box = ob,
  File "c:\Users\antho\Documents\Business\Projects\Django Projects\mms_env\lib\site-packages\django\db\models\fields\related_descriptors.py", line 369, in __set__
    super().__set__(instance, value)
  File "c:\Users\antho\Documents\Business\Projects\Django Projects\mms_env\lib\site-packages\django\db\models\fields\related_descriptors.py", line 266, in __set__
    raise ValueError(
ValueError: Cannot assign "(<OrderBox: testsku>,)": "Shipping.order_box" must be a "OrderBox" instance.

I can duplicate this in the python shell and it works, but in my views it keeps throwing this error.
If it matters I’m using Django 4.2 with a Postgres database.

2

Welcome @anthonycalvano !

You have extraneous commas on the end of these lines.
These are independent lines of code, they’re not part of a larger data structure.

3

Sorry about that. I was trying to solve another problem and when I changed the syntax to create the object in another way it gave me this error so I thought I was onto something. Thanks for the help. I’ll create a new post with my initial problem.