Django: IntegrityError null value violates not-null constraint - django

Question

In my django app, there is something strange that's happening & i'm not understanding.
I have two different tables (employeeProfile & purchaserShippingDetail) each has a field with the relation OneToOneField but with the 1st table (employeeProfile) in the field user that uses OneToOneField i can pass a string representation say Michael using api & i don't get an error but in my 2nd table that has similar structure when i add a string representation to i get
IntegrityError at /api/clients/shipping/
null value in column "owner_id" violates not-null constraint
1st Table model (works fine)
class employeeProfile(models.Model):
image = models.ImageField(default='default.png',upload_to='employee_photos/%Y/%m/%d/')
user = models.OneToOneField(CustomUser, on_delete=models.CASCADE, related_name="employee_profile")
phone_no = models.CharField(max_length=10, unique=True)
def __str__(self):
return self.user.name
2nd Table Model (The one that throws the "owner_id" violates not-null constraint error)
class purchaserShippingDetail(models.Model):
frequent_customer = models.BooleanField(default=False)
owner = models.OneToOneField(Purchaser, on_delete=models.CASCADE, related_name="purchaser_shipping")
address = models.CharField(max_length=12, blank=True)
zip_code = models.CharField(max_length=12, blank=True)
location = models.CharField(max_length=255)
def __str__(self):
return self.owner.name
Purchaser Model
class Purchaser(models.Model):
name = models.CharField(max_length=50)
phone = models.CharField(max_length=20, unique=True)
email = models.EmailField(max_length=255, unique=True, blank=True)
data_added = models.DateField(default=datetime.date.today)
def __str__(self):
return self.name
serializer for purchaserShippingDetail model
class purchaserShippingDetailSerializer(serializers.ModelSerializer):
owner = serializers.StringRelatedField(read_only=True)
class Meta:
model = purchaserShippingDetail
fields = '__all__'
Views.py for purchaserShippingDetail model
class purchaserShippingDetailsListCreateView(ListCreateAPIView):
serializer_class = purchaserShippingDetailSerializer
queryset = purchaserShippingDetail.objects.all()
EDIT: Added Purchaser model table

Answer 1

Could you please post the Purchaser model as well? There is a referenced field owner_id that we can't see in your post, which will explain more.
Have you added the owner field in a recent migration? It could be that you are adding a non-nullable field to a Table with existing rows, making those rows fail to satisfy the non-nullable condition.
You cannot add a default value on a OneToOneField so in that case you have to first add the field as null=True.
Then create an empty migration file to instantiate all rows on that table so no rows have a null value. Normally you do this by manage.py makemigrations app_name --empty.
That file could look something like
from django.db import migrations
def instantiate_owner(apps, schema_editor):
purchaserShippingDetail = apps.get_model("appname", "purchaserShippingDetail")
Purchaser = apps.get_model("some_other_app", "Purchaser")
for detail in purchaserShippingDetail.objects.all():
owner = Purchaser.objects.get(some_unique_criteria=detail.unique_criteria)
detail.owner = owner
detail.save()
class Migration(migrations.Migration):
dependencies = [
...,
]
operations = [
migrations.RunPython(instantiate_owner),
]
After that is complete you can remove the null=True in your model and make another migration.