set user foreign key default value as superuser or admin on on_delete=models.SET

As I was using on_delete=models.CASCADE with currentOwner in the asset model, whenever I deleted any user, all the assets owned by that user were getting deleted. I want the asset to be transferred to the superuser/admin. So I tried # MY SOLUTION but it is throwing me an error:

ValueError: Field 'id' expected a number but got 'admin'.

I think deleting previous migrations and running makemigrations and migrate commands might help, but that will probably erase all the data in the database, which I do not want to happen. Here are my User and asset models:

class User(PermissionsMixin, AbstractBaseUser):
    username = models.CharField(max_length=32, unique=True, )
    email = models.EmailField(max_length=32)
    gender_choices = [("M", "Male"), ("F", "Female"), ("O", "Others")]
    gender = models.CharField(choices=gender_choices, default="M", max_length=1)
    nickname = models.CharField(max_length=32, blank=True, null=True)

    is_active = models.BooleanField(default=True)
    is_staff = models.BooleanField(default=False)
    is_superuser = models.BooleanField(default=False)
    REQUIRED_FIELDS = ["email", "gender"]
    USERNAME_FIELD = "username"
    objects = User_manager()

    def __str__(self):
        return self.username

class asset(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False, null=False)
    asset_type = models.ForeignKey('assetType', on_delete=models.CASCADE, null=True)
    asset_name = models.CharField(max_length=30, null=True) #unique=True
    location = models.CharField(max_length=30, null=True)
    brand = models.CharField(max_length=30, null=True)
    purchase_year = models.PositiveIntegerField(blank=True, null=True)
    isActive = models.BooleanField(default=True, null=True)
    currentOwner = models.ForeignKey(User, default=User.objects.get(is_superuser=True).id, null=False, on_delete=models.SET_DEFAULT) # MY SOLUTION

Is there any way this can be solved?

CodePudding user response：

I read documentation here: https://docs.djangoproject.com/en/4.1/ref/models/fields/#django.db.models.SET in example you can find your case.

if you don't want to read documentation, the short answer:

For foreign key you should use on_delete=models.SET. AS argument models.SET get a function name.

in your case:

def get_superuser():
    su_user = User.objects.filter(is_superuser=True).first()  # if you have more than 1 superuser, this get the first in list.
    if su_user:
        return su_user
    raise DoesNotExist('Please add Super User')  # or you can create SU here

class asset(models.Model):
    ... # any staff here
    currentOwner = models.ForeignKey(User, on_delete=models.SET(get_superuser))

CodePudding user response：

The solution here was deleting all migrations except the first one, and then running makemigraions and migrate command. Since we never deleted the database, we never lost our records.