from django.db import models
class Position(models.Model):
    name = models.CharField(max_length=255, null=True, blank=True, default=" ")
    def __str__(self):
        return self.name
class Instructor(models.Model):
    name = models.CharField(max_length=64)
    surname = models.CharField(max_length=64)
    date_of_birth = models.DateField(null=True, blank=True)
    email = models.EmailField(unique=True, null=True)
    position = models.ForeignKey('Position', on_delete=models.SET_DEFAULT, default=1)
    is_active = models.BooleanField(default=True)
    def __str__(self):
        return self.name

 django.db.utils.IntegrityError: The row in table 'instructors_instructor' with primary key '1' has an invalid foreign key: instructors_instructor.position_id contains a value 'Django' that does not have a corresponding value in instructors_position.id.