OneToOneField RelatedObjectDoesNotExist exception

Using Django
1

Not sure if this is how it was designed but it looks like a bug for me :sweat_smile::
Here I have two models, the Review has a one-to-one relation with the OrderProduct

class OrderProduct(BaseModel):

    unit_price = models.DecimalField(
        _("unit price"), max_digits=9, decimal_places=0)
    count = models.PositiveIntegerField(_("count"))

    product = models.ForeignKey(
        ProductSKU, verbose_name=_("sku"), on_delete=models.CASCADE, related_name='order_products')
    order = models.ForeignKey(Order, verbose_name=_(
        'Order'), on_delete=models.SET_NULL, null=True, related_name='order_products')


class Review(BaseModel):

    class Star(models.IntegerChoices):
        VS = 5, _('Very satisfied')
        ST = 4, _('Satisfied')
        NT = 3, _('Neutral')
        US = 2, _('Unsatisfied')
        VN = 1, _('Very unsatisfied')

    star = models.PositiveSmallIntegerField(
        _("stars"), choices=Star.choices, default=5)
    comment = models.TextField(_("comment"))

    order_product = models.OneToOneField(
        OrderProduct, verbose_name=_("order product"), on_delete=models.CASCADE,related_name='review')

Now, I am trying to add a new property to OrderProduct to check if it has been reviewed.
According to the official doc: https://docs.djangoproject.com/en/3.1/topics/db/examples/one_to_one/
I add this code to my OrderProduct model:

    @property
    def is_reviewed(self):
        return hasattr(self, 'review')

I am expecting this property will return true or false when I refer to it, while I always got this exception:

In [38]: hasattr(ob,'review')
Out[38]: False

In [39]: ob.is_reviewed
---------------------------------------------------------------------------
RelatedObjectDoesNotExist                 Traceback (most recent call last)
<ipython-input-39-1cec125b3605> in <module>
----> 1 ob.is_reviewed

/usr/src/app/apps/order/models.py in is_reviewed(self)
    168
    169     @property
--> 170     def is_reviewed(self):
    171         return hasattr(self, 'review')
    172

/usr/local/lib/python3.8/site-packages/django/db/models/fields/related_descriptors.py in __get__(self, instance, cls)
    419
    420         if rel_obj is None:
--> 421             raise self.RelatedObjectDoesNotExist(
    422                 "%s has no %s." % (
    423                     instance.__class__.__name__,

RelatedObjectDoesNotExist: OrderProduct has no review.

What I have tried:
I tried to use try/except instead:

    @property
    def is_reviewed(self):
        try:
            self.review
            return False
        except ObjectDoesNotExist:
            return True

And still got the same RelatedObjectDoesNotExist exception.
I also tried to replace ObjectDoesNotExist with Review.DoesNotExist, or even only except, remove property decorator, remove related_name in oder_product, and all returned the same error message.

Also, when I try to create a Review object from related manager it throws the same error:

order_product = OrderProduct.objects.get(id=order_product_id)
order_product.review.create(star=star, comment=comment)

Why this exception cannot be caught? Or it is just my mistake on implementation? If so how to fix it? Just want to check whether the related object exists… Really appreciate your help! :smiling_face_with_three_hearts: :smiling_face_with_three_hearts:

2

You know what.
I restart the server and it fixed.
I was testing in ipython shell, exit and restart, now the is_reviewed return boolean as expected.
It is always good to know how stupid yourself could be therefore always keep humble… :innocent: :crazy_face:
Hope my experience will save your time on debugging meaningless issues.