CODEWITHSUNDEEP
pythondjangodjango-modelsforeign-keysdjango-related-manager
Anmol Batra
Anmol Batra

Reputation: 159

TypeError: Direct assignment to the reverse side of a related set is prohibited

I have a Django model 'Restaurant' which has a field parent_rest_id, which refers to one its parent restaurant which is saved in same table.

class Restaurant(DefaultColumns):
   name = models.CharField(null=False, max_length=40)
   restaurant_code = models.CharField(null=False, max_length=40, default='')
   parent_rest_id = models.ForeignKey(
                       'self',
                       null=False, 
                       db_column='parent_id',
                       default=0, 
                       related_name='parent_id',
                       on_delete=models.CASCADE
                    )
   restaurant_type = models.ForeignKey(
                       RestaurantType,
                       null=False, default='10', 
                       db_column='restaurant_type',
                       related_name='restaurant_type', 
                       on_delete=models.DO_NOTHING
                    )

Now when I try to create a row for it using Model.objects.create(**dict).

I get this error "TypeError: Direct assignment to the reverse side of a related set is prohibited. Use parent_id.set() instead."

I have made sure the parent_id is instance of Model Restaurant(Restaunt.objects.get(id=1))

Please let me know what I am doing wrong or I have created my model wrong, I am new to django.

PS: I don't have any customized serializer or model manager and DefaultColumns is parent class which inherits from model.Models

 >>>Model.objects.create(**filtered_dict)
Traceback (most recent call last):
  File "C:\Program Files\JetBrains\PyCharm Community Edition 2020.1\plugins\python-ce\helpers\pydev\_pydevd_bundle\pydevd_exec2.py", line 3, in Exec
    exec(exp, global_vars, local_vars)
  File "<input>", line 1, in <module>
  File "C:\Users\Nerd\Documents\myvirtualenv\lib\site-packages\django\db\models\base.py", line 495, in __init__
    _setattr(self, prop, kwargs[prop])
  File "C:\Users\Nerd\Documents\myvirtualenv\lib\site-packages\django\db\models\fields\related_descriptors.py", line 546, in __set__
    % self._get_set_deprecation_msg_params(),
TypeError: Direct assignment to the reverse side of a related set is prohibited. Use parent_id.set() instead.

>>> filtered_dict
{'name': 'A2b', 'email': '', 'parent_id': <Restaurant: Default, >, 'restaurant_type': <RestaurantType: Store>, 'phone': '', 'address': '', 'city': '', 'postal_code': '', 'restaurant_code': 'A2B'}


>>>Model
<class 'Restaurant'>

Upvotes: 3

Views: 3253

Answers (1)

Anmol Batra
Anmol Batra

Reputation: 159

I was able to resolve this error, since I have foreign key reference to the same table to which the key belongs to. So giving 'related name' was creating a backward relation with the model. Which was actually not needed. In Django if we give relate_name = '+', then Django will skip the creation of reverse relation. Hence this approach resolved my issue.

Upvotes: 2

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