How to check the PK of a foreign-key relationship without loading the related model; how to compare two objects

[merlinz01]

I have put my questions in the comments in the below code. I did not find answers in the documentation.

class User(Model):
    username = CharField(max_length=255, primary_key=True)
    organization: ForeignKeyNullableRelation[Organization] = ForeignKeyField(
        "models.Organization",
        related_name="users",
        on_delete=OnDelete.RESTRICT,
        null=True,
    )

    @property
    def is_admin(self):
        # Does this load the organization model?
        # Is there a way to check the foreign key itself for being null without loading the referenced model?
        return self.organization is None

    def may_create_user(self, user: "User_Pydantic"):
        if self.is_admin:
            return True
        org = user.organization
        if org is None:
            return False
        # Is this the correct way to compare two models?
        # Does tortoise do original-object-return so that we can test using `is`?
        return org == self.organization

[Abdeldjalil-H]

Hi @merlinz01. I know this is late, but in case you still didn't find an answer and for other poeple using Tortoise orm.
When you use a foreign key field called fk_field, tortoise will use fk_field_id to store the value of the related model id. The fk_field is used to load the relation.
For you're question, is_admin does not load the organization. You need to use fetch_related to load it. But you can check if the foreign key is null without loading it. Here's how you can do it:

@property
def is_admin(self):
    return self.organization_id is None

Same thing for your second question.

[merlinz01]

I had eventually figured it out, but thanks for the answer @Abdeldjalil-H.

To clarify the answer to the second question, I don't believe Tortoise does original-object-return, so the correct way to check the identity of two objects is to compare their primary key field.