# ValueError at /signup/ Cannot assign "\<User: prosenjit\>": "Referral.parent" must be a "Referral" instance

**URL:** <https://forum.djangoproject.com/t/valueerror-at-signup-cannot-assign-user-prosenjit-referral-parent-must-be-a-referral-instance/17892>\
**Category:** Getting Started\
**Created:** [December 29, 2022, 5:27am UTC](https://forum.djangoproject.com/t/valueerror-at-signup-cannot-assign-user-prosenjit-referral-parent-must-be-a-referral-instance/17892 "2022-12-29T05:27:45Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![ProsenjitKumar](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/prosenjitkumar/32/11298_2.png) [@ProsenjitKumar](https://forum.djangoproject.com/u/ProsenjitKumar)\
**Post date:** [December 29, 2022, 5:27am UTC](https://forum.djangoproject.com/t/valueerror-at-signup-cannot-assign-user-prosenjit-referral-parent-must-be-a-referral-instance/17892/1 "2022-12-29T05:27:45Z")

</div>

After reading a lot of answers similar to this problem I got a specific error in every single case. In the following, I have attached my mandatory code.

# Models.py

```auto
import uuid
import enum
from django.db import models
from django.utils import timezone, translation
from django.conf import settings
from django.core.validators import MinValueValidator, MaxValueValidator
from django.contrib.auth import get_user_model
from django.contrib.contenttypes.models import ContentType
from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation

from django_numerators.models import NumeratorMixin
from mptt.models import MPTTModel, TreeForeignKey, TreeManager

_ = translation.gettext_lazy
from .utils import generate_ref_code

class Referral(NumeratorMixin, MPTTModel, models.Model):
    class Meta:
        verbose_name = _('Referral')
        verbose_name_plural = _('Referral')
        unique_together = ('parent', 'account')

    limit = 3

    parent = TreeForeignKey(
        'self', null=True, blank=True,
        on_delete=models.SET_NULL,
        related_name='downlines',
        verbose_name=_('Up Line'))
    account = models.OneToOneField(
        get_user_model(),
        on_delete=models.CASCADE,
        verbose_name=_('account'))
    balance = models.DecimalField(
        default=0,
        max_digits=15,
        decimal_places=2,
        editable=False,
        verbose_name=_("Balance"))
    created_at = models.DateTimeField(
        default=timezone.now, editable=False)
    code = models.CharField(max_length=12, blank=True)

    def __str__ (self):
        return (
            self.account.username
            if self.account.get_full_name() in ['', None]
            else self.account.get_full_name()
        )

    def update_balance(self, balance):
        self.balance = balance
        self.save()

    def get_referral_limit(self):
        return getattr(settings, 'REFERRAL_DOWNLINE_LIMIT', None) or self.limit

    def get_uplines(self):
        return self.get_ancestors(include_self=False, ascending=True)[:self.get_referral_limit()]

    def save(self, *args, **kwargs):
        if self.code == "":
            code = generate_ref_code()
            self.code = code
        super().save(*args, **kwargs)

```

**Everything is working well and 100% worked if I add foreignkey instead of TreeForeignKey in the parent field**

```auto
parent = models.ForeignKey(User, on_delete=models.CASCADE, blank=True, null=True, related_name='ref_by')

```

Instead Of

```auto
parent = TreeForeignKey(
            'self', null=True, blank=True,
            on_delete=models.SET_NULL,
            related_name='downlines',
            verbose_name=_('Up Line'))

```

But I need TreeForeignKey because of my **multilevel referral system**.

```auto
# utils.py

import uuid
import json
from django.core.serializers.json import DjangoJSONEncoder
from uuid import UUID
import random

def generate_ref_code():
    code = str(uuid.uuid4()).replace("-", "")[:12]

    return code

```

# signals.py

```auto
from .models import Referral
from django.contrib.auth.models import User
from django.db.models.signals import post_save
from django.dispatch import receiver

@receiver(post_save, sender=User)
def post_save_create_profile(sender, instance, created, *args, **kwargs):
    if created:
        Referral.objects.create(account=instance)

```

# views.py

```auto
@csrf_protect
def signup_view(request):
    profile_id = request.session.get('ref_profile')
    print('profile_id', profile_id)
    form = SignupForm(request.POST or None)
    if form.is_valid():
        if profile_id is not None:
            recommended_by_profile = Referral.objects.get(id=profile_id)
            print("recommended_by_profile", recommended_by_profile)

            instance = form.save()
            print("instance saved", instance)
            registered_user = User.objects.get(id=instance.id)
            print("registered_user", registered_user)
            registered_profile = Referral.objects.get(account=registered_user)
            print("registered_profile", registered_profile)
            registered_profile.parent = recommended_by_profile.account
            print("registered_profile.parent", registered_profile.parent)
            # print("registered_profile.user", registered_profile.user)
            print("registered_profile.account", registered_profile.account)
            print("recommended_by_profile.parent", recommended_by_profile.parent)
            # print("recommended_by_profile.user", recommended_by_profile.user)
            print("recommended_by_profile.account", recommended_by_profile.account)
            registered_profile.save()
            print("registered_profile it's saved", registered_profile)
        else:
            print("Referral not working")
            form.save()
        username = form.cleaned_data.get('username')
        password = form.cleaned_data.get('password1')
        user = authenticate(username=username, password=password)
        login(request, user)
        return redirect('main_view')
    context = {
        'form': form
    }
    return render(request, 'signup.html', context)

```

I have also attached the image and video together of the error where you can see the specific one. Here are the main issues with a data type that is not passing on the “parent” field when using “TreeForeignKey”.

 ![error](https://us1.discourse-cdn.com/flex026/uploads/djangoproject/original/2X/1/1f40b87ebf08e27861d1b2829fbf557d2a61965f.png)

[The Video Link Is Below](https://www.youtube.com/watch?v=4RKmgsXbGEk)

**[The Video](https://www.youtube.com/watch?v=4RKmgsXbGEk)**

Any kind of help or suggestion would be appreciated related to the question.

Thanks

---

<div class="post-metadata">

**Author:** ![KenWhitesell](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/kenwhitesell/32/280_2.png) [@KenWhitesell](https://forum.djangoproject.com/u/KenWhitesell)\
**Post date:** [December 29, 2022, 12:07pm UTC](https://forum.djangoproject.com/t/valueerror-at-signup-cannot-assign-user-prosenjit-referral-parent-must-be-a-referral-instance/17892/2 "2022-12-29T12:07:41Z")

</div>

> [@ProsenjitKumar](#):
>
> ```auto
> parent = TreeForeignKey(
> 'self', null=True, blank=True,
> 
> ```

What type of object is `self` going to be in this instance? (What is the error message telling you?)

---

<div class="post-metadata">

**Author:** ![ProsenjitKumar](https://sea2.discourse-cdn.com/flex026/user_avatar/forum.djangoproject.com/prosenjitkumar/32/11298_2.png) [@ProsenjitKumar](https://forum.djangoproject.com/u/ProsenjitKumar)\
**Post date:** [December 29, 2022, 1:09pm UTC](https://forum.djangoproject.com/t/valueerror-at-signup-cannot-assign-user-prosenjit-referral-parent-must-be-a-referral-instance/17892/3 "2022-12-29T13:09:43Z")

</div>

I wanted to send a user instance that should send a name. That will assign as a parent of a new user who will use the code.

But the “parent” name is the default “Mptt Model” field that I can’t change. And the parent field always sends me the parent’s name or “None”. But should be assigned the refer user name of the new user.

I tried to use it to send the **parent id** instead of the **parent** directly. In the view file, I tried to add this line  
\*\*

> registered\_profile.parent\_id = recommended\_by\_profile.account.pk

\*\*  
It saved the name according to the id number. Randomly assigned the parent name. In this case, maybe I’m very close to the solution if I can send the exact user-id as a parent.

Finally, it’s working well if I send directly the id number as the parent.

> registered\_profile.parent\_id = profile\_id