Automated related ForeignKey Models in ModelSchema

Can related models be handled automatically?

Model

class ExampleModel(models.Model):
    relation = models.ForeignKey(SomeOtherModel, on_delete=models.PROTECT, related_name='example')

ModelSchema

class ExampleSchema(ModelSchema):
   class Config:
       model = models.ExampleModel
       model_fields = ['id', 'relation']

API

@api.post('/example')
def create_example(request, payload: schemas.ExampleSchema):
    pl = payload.dict()
    relation = get_object_or_404(SomeOtherModel, id=payload.relation)
    pl['relation'] = relation
    example = models.ExampleModel.objects.create(**pl)
    return {'id': example.id}

The above example works with the payload {'relation_id': 4} if the object with ID 4 exists.

Question 1 Is there any specific reason why the field has to be named relation_id in the payload and not just relation?

Question 2 In the API, is it really necessary to do

    pl = payload.dict()
    relation = get_object_or_404(SomeOtherModel, id=payload.relation)
    pl['relation'] = relation

or can that be somehow done automatically? It seems that writing the get_object_or_404() is currently needed, or can that be omitted with an other apporach?

[chrisbodon]

I´m using that workaround but it gets this when I try to post:

ValueError: Cannot assign "18": "Activity.town" must be a "Town" instance.

My code:

URLS.PY

@api.post("/activities", response=ActivitySchema)
def create_activities(request, data: ActivitySchema):
	obj = Activity.objects.create(**data.dict())
	return obj

The data Im trying to post

{icon_id: '6', name: 'mn bnb', highlight: false, town_id: 18}

SCHEMAS.PY

class ActivitySchema(ModelSchema):
	town_id: int = None
	icon_id: int = None
	
	class Config:
		model = Activity
		model_fields = "__all__"

MODELS.PY

class Activity(models.Model):
	town = models.ForeignKey(Town, on_delete=models.CASCADE, null=False)
	icon = models.ForeignKey(MediaIcon, on_delete=models.CASCADE, null=False)
	name = models.CharField(max_length=255, null=False)
	highlight = models.BooleanField(default=False)
	
	def __str__(self):
		return self.name

[vitalik]

@fantasticle

… This will yield a ninja.errors.ConfigError: Field(s) {‘my_field’} are not in model.

I think it should not - can you give your example ?

Maybe workaround for you case would be to set FK ids as attributes:

class MyModelSchema(ModelSchema):
  some_relation_id: int
  other_relation_id: int
  class Config:
    model = MyModel
    fields = ['some_char_field']
...

@api.post(...)
def foo(request, payload: MyModelSchema)
      obj = MyModel(**payload.dict())
      obj.save()