[BUG] ModelSchema does not support ForeignKey as `field_id`

[asaff1]

Describe the bug
A clear and concise description of what the bug is.

Versions (please complete the following information):

• Python version: 3.11
• Django version: 4.2.33
• Django-Ninja version: 1.1.0
• Pydantic version: 2.11.4

Not sure if that intentional, but that doesn't make a lot of sense:

class OrderOut(ModelSchema)

   class Meta:
       model = Order
       fields = [ "user_id"]  # user_id is foreignkey on Order model

Serialization fails with error like:
ninja.errors.ConfigError: DjangoField(s) {'user_id'} are not in model <class 'app.models.Order'>

However if I change the field to user instead of user_id it does work. Why is that? I believe user_id should also work.

[wilkerdossantos]

It seems there’s a small misunderstanding here, user_id is not an actual field in the Django model, but an automatically generated attribute provided by the ORM.

In the model definition, the field is declared as user, for example:

class Order(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE)

In this case:

• user is the model field (used by serializers, forms, and the ORM).
• user_id is just the database column automatically created by Django to store the foreign key value.

That’s why using user works correctly in the serializer, while user_id raises a ConfigError, the serializer expects model fields, not the underlying database column names.

[asaff1]

@wilkerdossantos what you say is clear. Still I think there should be a way to include foreign key ids i ModelSchema because this is how it is commonly used in django, in this case, user is expected to be an object, user_id a number. In django ninja, user field will be a number...