Django Ninja fails with ForeignObject fields: AttributeError 'ForeignObjectRel' object has no attribute 'help_text'

[blasferna]

Django Ninja fails to generate ModelSchema when using Django's ForeignObject field, which is the recommended workaround for composite primary key relationships in Django 5.2 documentation.

Error:

AttributeError: 'ForeignObjectRel' object has no attribute 'help_text'

The models:

Note: I'm don't using the composite primary key in this example.

from django.db import models

class Order(models.Model):
    # ... (fields can be omitted for brevity)
    pass

class Product(models.Model):
    # ... (fields can be omitted for brevity)
    pass

class OrderDetail(models.Model):
    order = models.ForeignObject(
        Order,
        on_delete=models.CASCADE,
        from_fields=["order_id"],
        to_fields=["id"],
        related_name="details"
    )
    product = models.ForeignKey(Product, on_delete=models.CASCADE)
    quantity = models.PositiveIntegerField()

The endpoints:

from ninja import ModelSchema, NinjaAPI
from .models import Order

api = NinjaAPI()


class OrderSchema(ModelSchema):
    class Meta:
        model = Order
        fields = "__all__"


@api.get("/orders", response=list[OrderSchema])
def list_orders(request):
    return Order.objects.all()

Django Ninja cannot handle ForeignObject fields because ForeignObjectRel objects don't have the same attributes as ForeignKey relations.

A workaround is to explicitly define the fields in the ModelSchema, but I want to use the fields = "__all__" in the schema definition.

Reproduction

A minimal reproduction case is available at: https://github.com/blasferna/django-ninja-foreignobject-issue

To reproduce:

1. Clone the reproduction repository
2. Run uv sync
3. Run uv run manage.py runserver

The error occurs immediately when Django tries to import the API endpoints.

Versions:

• Python version: 3.12
• Django version: 5.2.5
• Django-Ninja version: 1.4.3
• Pydantic version: 2.11.7

[JaeHyuckSa]

@vitalik Hi! I’d be happy to work on this if it’s still available—could you assign me?