django-fsm FSMKeyField transition identifier

Question

I'm currently facing an issue while trying to define a transition identifier using the 'type' field of a ForeignKey model in Django. After carefully reading the documentation, I noticed that the examples provided primarily utilize the primary key for transition identifiers.

Here are some examples: Test examples

I'm wondering if anyone has experience or insights into how to specify a transition identifier using the 'type' field of my ForeignKey model (Stage).

Any guidance or examples demonstrating the correct approach in such scenarios would be greatly appreciated. Thank you!

class Stage(models.Model):
    class Type(models.TextChoices):
        SUBSCRIBED = (
            "SUBSCRIBED",
            _("Subscribed"),
        )
        SELECTED = (
            "SELECTED",
            _("Selected"),
        )
        APPROVED = (
            "APPROVED",
            _("Approved"),
        )


    name = models.CharField(max_length=255)
    type = models.CharField(
        max_length=255,
        choices=Type.choices,
        default=Type.CUSTOM,
    )


class Recruitment(models.Model):
    class Status(models.TextChoices):
        ACTIVE = ("ACTIVE", _("Active"))
        INACTIVE = ("INACTIVE", _("Inactive"))

    stage = FSMKeyField(Stage, on_delete=models.RESTRICT, protected=True)


    @transition(
        field=stage,
        source=[Stage.Type.SUBSCRIBED], #This not works
        target=Stage.Type.SELECTED,
    )
    def select(self, description=None, by=None):
        return "Candidate was selected!"

I want to discover a way to implement a feature.