# OneToOneField RelatedObjectDoesNotExist exception

**URL:** <https://forum.djangoproject.com/t/onetoonefield-relatedobjectdoesnotexist-exception/5551>\
**Category:** Using Django\
**Created:** [December 4, 2020, 7:34am UTC](https://forum.djangoproject.com/t/onetoonefield-relatedobjectdoesnotexist-exception/5551 "2020-12-04T07:34:54Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![convers39](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/convers39/32/2703_2.png) [@convers39](https://forum.djangoproject.com/u/convers39)\
**Post date:** [December 4, 2020, 7:34am UTC](https://forum.djangoproject.com/t/onetoonefield-relatedobjectdoesnotexist-exception/5551/1 "2020-12-04T07:34:54Z")

</div>

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

```auto
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/](https://docs.djangoproject.com/en/3.1/topics/db/examples/one_to_one/)  
I add this code to my OrderProduct model:

```auto
    @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:

```auto
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:

```auto
    @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:

```auto
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! 🥰 🥰

---

<div class="post-metadata">

**Author:** ![convers39](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/convers39/32/2703_2.png) [@convers39](https://forum.djangoproject.com/u/convers39)\
**Post date:** [December 4, 2020, 8:01am UTC](https://forum.djangoproject.com/t/onetoonefield-relatedobjectdoesnotexist-exception/5551/2 "2020-12-04T08:01:20Z")

</div>

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… 😇 🤪  
Hope my experience will save your time on debugging meaningless issues.