How to make changes to the database? (DRF)

Question

In the model of the Post object, I have field created = models.DateTimeField field (auto_now_add = True)

There is another field end_time, in which - today's date + 1 month in advance. That is, if a post was created, then it will have today's date in the created field (January 5, 2020), and in the end_time field it will be a month ahead (February 5, 2020).

def next_month():
    now = timezone.now()
    return now + relativedelta(months=+1)

end_time = models.DateTimeField(default=next_month, blank=True, editable=False)

To all this, I'm need to add the is_actual field, in which -

  @property
  def is_actual(self):
    return bool(self.end_time and self.end_time > now())

But in this case, I can not use the filter to display the fields, where is_actual == true. For me, a filter using this field is very important.

What needs to be done so that I can apply a filter by the is_actual field? As far as I understand, here you need to make once a day, for example, changes to the database. But how? To write some kind of custom script, or to do it somehow using Django methods?

Answer 1

I would suggest to make "is_actual = model.BooleanField(default=False)" and do what necessary in the clean method. For example:

class MyModel(models.Model):
      is_active=models.BooleanField(default=False)
      ...
      def clean(self):
          super(MyModel, self).clean()
          if self.end_time:
             self.is_active = self.end_time > now()

Check here for more insights: https://docs.djangoproject.com/en/3.0/ref/models/instances/#django.db.models.Model.clean

Answer 2

Filter with:

from django.db.models.functions import Now

# is_actual is True
MyModel.objects.filter(
    end_time__gt=Now()
)

# is_actual is False
MyModel.objects.filter(
    end_time__lte=Now()
)