CODEWITHSUNDEEP
django-models
nmajoros
nmajoros

Reputation: 127

Model field not updating in save()

In my Django MyModel I've created a new field last_status_change (a timestamp). Should be updated when that status changes.

However, even when a print shows that last_status_change is computed correctly, it doesn't get saved. Is any field modification prohibited within save? What's the reason behind it? How to work around it?


class MyModel(models.Model):
  first_name = models.CharField(max_length=100, verbose_name='Name')
  confirmation_status = models.CharField(
        choices=CONFIRMATION_STATUS_CHOICES,
        default='registered', max_length=20
    )
  last_status_change = models.DateTimeField(null=True, blank=True)

  def save(self, *args, **kwargs):
    if self.pk:
      original = MyModel.objects.get(pk=self.pk)
      if original.confirmation_status != self.confirmation_status:
        last_status_change = datetime.now()
    return super(MyModel, self).save(*args, **kwargs)

Upvotes: 1

Views: 38

Answers (1)

willeM_ Van Onsem
willeM_ Van Onsem

Reputation: 476574

You need to assign it to the self object, so:

from django.utils import timezone


class MyModel(models.Model):
    first_name = models.CharField(max_length=100, verbose_name='Name')
    confirmation_status = models.CharField(
        choices=CONFIRMATION_STATUS_CHOICES, default='registered', max_length=20
    )
    last_status_change = models.DateTimeField(null=True, blank=True)

    def save(self, *args, **kwargs):
        if self.pk:
            original = MyModel.objects.get(pk=self.pk)
            if original.confirmation_status != self.confirmation_status:
                self.last_status_change = timezone.now()
        return super().save(*args, **kwargs)

Upvotes: 1

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