django.db.utils.IntegrityError: insert or update on table "authtoken_token" violates foreign key constraint

Question

I have a little problem on django rest framework in saving data (with token), why i am receiving this error? insert or update on table "authtoken_token" violates foreign key constraint "authtoken_token_user_id_35299eff_fk_auth_user_id" thanks in advance.

this is my serializers.py

class RegistrationSerializer(serializers.ModelSerializer):

    password2               = serializers.CharField(style={'input_type': 'password'}, write_only=True)

    class Meta:
        model = Account
        fields = ['email', 'username', 'password', 'password2']
        extra_kwargs = {
                'password': {'write_only': True},
        }   


    def save(self):

        account = Account(
                    email=self.validated_data['email'],
                    username=self.validated_data['username']
                )
        password = self.validated_data['password']
        password2 = self.validated_data['password2']
        if password != password2:
            raise serializers.ValidationError({'password': 'Passwords must match.'})
        account.set_password(password)
        account.save()
        return account

my views.py

@api_view(['POST', ])
def registration_view(request):

    if request.method == 'POST':
        serializer = RegistrationSerializer(data=request.data)
        data = {}
        if serializer.is_valid():
            account = serializer.save()
            data['response'] = 'successfully registered new user.'
            data['email'] = account.email
            data['username'] = account.username
            token = Token.objects.get(user=account).key
            data['token'] = token
        else:
            data = serializer.errors
        return Response(data)

my models.py

class MyAccountManager(BaseUserManager):
    def create_user(self, email, username, password=None):
        if not email:
            raise ValueError('Users must have an email address')
        if not username:
            raise ValueError('Users must have a username')

        user = self.model(
            email=self.normalize_email(email),
            username=username,
        )

        user.set_password(password)
        user.save(using=self._db)
        return user

    def create_superuser(self, email, username, password):
        user = self.create_user(
            email=self.normalize_email(email),
            password=password,
            username=username,
        )
        user.is_admin = True
        user.is_staff = True
        user.is_superuser = True
        user.save(using=self._db)
        return user


class Account(AbstractBaseUser):
    email                   = models.EmailField(verbose_name="email", max_length=60, unique=True)
    username                = models.CharField(max_length=30, unique=True)
    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)


    USERNAME_FIELD = 'email'
    REQUIRED_FIELDS = ['username']

    objects = MyAccountManager()

    def __str__(self):
        return self.email

    # For checking permissions. to keep it simple all admin have ALL permissons
    def has_perm(self, perm, obj=None):
        return self.is_admin

    # Does this user have permission to view this app? (ALWAYS YES FOR SIMPLICITY)
    def has_module_perms(self, app_label):
        return True


@receiver(post_save, sender=settings.AUTH_USER_MODEL)
def create_auth_token(sender, instance=None, created=False, **kwargs):
    if created:
        Token.objects.create(user=instance)

this is the full traceback

Traceback:

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/backends/utils.py" in _execute
  84.                 return self.cursor.execute(sql, params)

The above exception (insert or update on table "authtoken_token" violates foreign key constraint "authtoken_token_user_id_35299eff_fk_auth_user_id"
DETAIL:  Key (user_id)=(7) is not present in table "auth_user".
) was the direct cause of the following exception:

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/views/decorators/csrf.py" in wrapped_view
  54.         return view_func(*args, **kwargs)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/views/generic/base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/rest_framework/views.py" in dispatch
  505.             response = self.handle_exception(exc)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/rest_framework/views.py" in handle_exception
  465.             self.raise_uncaught_exception(exc)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/rest_framework/views.py" in raise_uncaught_exception
  476.         raise exc

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/rest_framework/views.py" in dispatch
  502.             response = handler(request, *args, **kwargs)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/rest_framework/decorators.py" in handler
  50.             return func(*args, **kwargs)

File "/home/schoolsite/schoolsitedir/homepage/api/views.py" in registration_view
  27.           account = serializer.save()

File "/home/schoolsite/schoolsitedir/homepage/api/serializers.py" in save
  34.       account.save()

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/contrib/auth/base_user.py" in save
  66.         super().save(*args, **kwargs)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/base.py" in save
  741.                        force_update=force_update, update_fields=update_fields)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/base.py" in save_base
  790.                 update_fields=update_fields, raw=raw, using=using,

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/dispatch/dispatcher.py" in send
  175.             for receiver in self._live_receivers(sender)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/dispatch/dispatcher.py" in <listcomp>
  175.             for receiver in self._live_receivers(sender)

File "/home/schoolsite/schoolsitedir/homepage/models.py" in create_auth_token
  86.         Token.objects.create(user=instance)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/manager.py" in manager_method
  82.                 return getattr(self.get_queryset(), name)(*args, **kwargs)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/query.py" in create
  422.         obj.save(force_insert=True, using=self.db)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/rest_framework/authtoken/models.py" in save
  33.         return super().save(*args, **kwargs)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/base.py" in save
  741.                        force_update=force_update, update_fields=update_fields)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/base.py" in save_base
  779.                 force_update, using, update_fields,

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/base.py" in _save_table
  870.             result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/base.py" in _do_insert
  908.                                using=using, raw=raw)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/manager.py" in manager_method
  82.                 return getattr(self.get_queryset(), name)(*args, **kwargs)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/query.py" in _insert
  1186.         return query.get_compiler(using=using).execute_sql(return_id)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/models/sql/compiler.py" in execute_sql
  1335.                 cursor.execute(sql, params)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/backends/utils.py" in execute
  99.             return super().execute(sql, params)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/backends/utils.py" in execute
  67.         return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/backends/utils.py" in _execute_with_wrappers
  76.         return executor(sql, params, many, context)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/backends/utils.py" in _execute
  84.                 return self.cursor.execute(sql, params)

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/utils.py" in __exit__
  89.                 raise dj_exc_value.with_traceback(traceback) from exc_value

File "/home/schoolsite/schoolsitedir/env/lib/python3.6/site-packages/django/db/backends/utils.py" in _execute
  84.                 return self.cursor.execute(sql, params)

Exception Type: IntegrityError at /api/registration_view/
Exception Value: insert or update on table "authtoken_token" violates foreign key constraint "authtoken_token_user_id_35299eff_fk_auth_user_id"
DETAIL:  Key (user_id)=(7) is not present in table "auth_user".

here is my settings.py

INSTALLED_APPS = [
    
    'django_tables2',
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'django.contrib.humanize',
    'rest_framework',
    'rest_framework.authtoken',
    'homepage',
]
AUTH_USER_MODEL = 'homepage.Account'
REST_FRAMEWORK = {
    'DEFAULT_AUTHENTICATION_CLASSES': [
        'rest_framework.authentication.TokenAuthentication',

    ]
}

this is my filetree

my file

myproject
     |_homepage
       |_ __init__.py
       |_admin.py
       |_models.py
       |_apps.py
       |_views.py
     |_schoolsite
       |_ __init__.py
       |_settings.y
       |_urls.py
       |_wsgi.py

Answer 1

WARNING! Migrate "zero" drop all tokens!

Works for me

./manage.py migrate authtoken zero

and then

./manage.py migrate authtoken

Answer 2

For some reason in your db structure auth_user is still set as ForeignKey. As you are using Account as your user model, it should be something like account_user it might be some migration problem. My best guess is that you had a previous user model(default one may be) and in mid project you created/migrated your new user model (Account). There may be old data present in your db. If that's the case, I think quickest solution would be to remove all the migration from Account app and migrate again (to let django create all the db from scratch)

note: of course this means, you have to delete all the current users.