How to get rid of migrations error in Django?

Question

PostgreSQL

I am using postgresql. Added an additional Techgroup model and created a foreignkey for it in the existing Technology table. I get an error when I try to apply migrations.

django.db.utils.IntegrityError: column "group_id" contains null values

models.py

class Techgroup(models.Model):
    """ Group of technology """

    name = models.CharField('group_name', max_length=32, unique=True)

    def __str__(self):
        return self.name


class Technology(models.Model):
    """Technologies."""

    name = models.CharField('technology name', max_length=32, unique=True)
    group = models.ForeignKey(Techgroup, on_delete=models.CASCADE, related_name="group")

    def __str__(self):
        return self.name

How to get around this problem?

Answer 1

- change field to
- make a migration.
- run through the objects of the Technology model, assigning the appropriate Group
- make another migration, changing the field to

group = models.ForeignKey(Techgroup, on_delete=models.CASCADE, related_name="group")