Django 3.0.3 IntegrityError FOREIGN KEY constraint failed when making changes to db

Question

I have two models in my database, an 'Account' model (which is a custom user model) and a 'Return' model.

My database worked fine up to the point of adding the 'Return' model, which has a ForeignKey relationship with the 'User' model, which I suspect is causing the problem. (Each return belongs to an existing user. In the admin panel, the option box is populated with existing users so I thought this was working correctly?)

Appreciate any help with this!

Error:

IntegrityError at /admin/returns/return/add/

FOREIGN KEY constraint failed

Request Method: POST Request URL: http://127.0.0.1:8000/admin/returns/return/add/ Django Version: 3.0.3 Exception Type: IntegrityError Exception Value:

FOREIGN KEY constraint failed

Here is my Return app's models.py:

from django.db import models

from django.contrib.auth import get_user_model
User = get_user_model()

# Create your models here.
class Return(models.Model):
    user = models.ForeignKey(User, related_name="returns", on_delete=models.PROTECT)
    created_at = models.DateTimeField(auto_now=True)
    last_edited = models.DateTimeField(null=True)

    TAX_YEAR_CHOICES = [
    ('2019', '2019'),
    ('2020', '2020'),
    ('2021', '2021'),
    ]

    tax_year_ending = models.CharField(
        choices=TAX_YEAR_CHOICES,
        max_length=4,
        blank=False,
        null=False,
    )

    RETURN_STATUS_CHOICES = [
    ('1', 'In progress'),
    ('2', 'Completed, awaiting review'),
    ('3', 'Completed, under review'),
    ('4', 'Completed, awaiting client action'),
    ('5', 'Submitted to HMRC'),
    ]

    return_status = models.CharField(
        choices=RETURN_STATUS_CHOICES,
        max_length=1,
        default=1,
        blank=False,
        null=False,
    )

Here is my custom user class (also setup in settings.py):

class Account(AbstractBaseUser):
    email = models.EmailField(verbose_name='email', max_length=60, unique=True) # tells Django this is the unique ID

    #following required for the AbstractBaseUser class
    date_joined = models.DateTimeField(verbose_name='date joined', auto_now_add=True)
    last_login = models.DateTimeField(verbose_name='last login', auto_now=True)
    is_admin = models.BooleanField(default=False)
    is_active = models.BooleanField(default=True)
    is_staff = models.BooleanField(default=False)
    is_superuser = models.BooleanField(default=False)

    #tell django we want to use email as our username field (for logins)
    USERNAME_FIELD = 'email'

    #tells Django to user AccountManager
    objects = AccountManager()

    #tell django which fields are required on registration:
    #REQUIRED_FIELDS = []

    #what to return when we print the Account object
    def __str__(self):
        return self.email

#following required for AbstractBaseUser class
    #does the user have permissions, yes if is_admin
    def has_perm(self, perm, obj=None):
        return self.is_admin

    def has_module_perms(self, app_label):
        return True

Here is the post request information from the errog log: user

'3'

last_edited_0

'2020-05-03'

last_edited_1

'13:01:23'

tax_year_ending

'2019'

return_status

'3'

_addanother

'Save and add another'

(I have confirmed that there is a user with pk '3')

Thanks again, really appreciate it.

Answer 1

You need to record the instance of user on behalf of pk number:

User.objects.get(pk=3)