How to change status field automatically from 1 to 0 when end_time is reached

Question

This is my Auction model:

class Auction(models.Model):
    auction_id = models.AutoField(primary_key=True)
    crop = models.ForeignKey(Crop, on_delete=models.CASCADE)
    image = models.ImageField(upload_to="crop-image")
    farmer = models.ForeignKey(User, on_delete=models.CASCADE, limit_choices_to={'user_type': 'farmer'})
    creation_time = models.DateTimeField(auto_now_add=True)
    end_date = models.DateField()
    end_time = models.TimeField()
    status = models.BooleanField(default=True)
    qty = models.IntegerField()
    unit = models.CharField(max_length=10, choices=[('kg', 'Kilograms'), ('tonne', 'Metric Tons'), ('bushel', 'Bushels'), ('crate', 'Crates')])
    hammer_price = models.IntegerField()
    description = models.CharField(max_length=200)
    payment = models.BooleanField(default=False)

    class Meta:
        verbose_name_plural = "Auctions"

    def __str__(self):
        return self.crop.title

When combined end_date and end_time is reached, status which is by default set to 1 on auction creation should be changed to 0.

Answer 1

I would simply not add a status, but check if the end timestamp is used. By defining a status field, you introduce data duplication, you specify the same thing twice.

You probably should also combine the date and the time, since a timestamp is more than a date and a time because of daylight saving time for example.

from django.conf import settings


class Auction(models.Model):
    auction_id = models.AutoField(primary_key=True)
    crop = models.ForeignKey(Crop, on_delete=models.CASCADE)
    image = models.ImageField(upload_to='crop-image')
    farmer = models.ForeignKey(
        settings.AUTH_USER_MODEL,
        on_delete=models.CASCADE,
        limit_choices_to={'user_type': 'farmer'},
    )
    creation_time = models.DateTimeField(auto_now_add=True)
    end_timestamp = models.DateTimeField()
    # no status
    qty = models.IntegerField()
    unit = models.CharField(
        max_length=10,
        choices=[
            ('kg', 'Kilograms'),
            ('tonne', 'Metric Tons'),
            ('bushel', 'Bushels'),
            ('crate', 'Crates'),
        ],
    )
    hammer_price = models.IntegerField()
    description = models.CharField(max_length=200)
    payment = models.BooleanField(default=False)

    class Meta:
        verbose_name_plural = 'Auctions'

    def __str__(self):
        return self.crop.title

So we can for example get all Auctions that are still active with:

from django.db.models.functions import Now

Auction.objects.filter(end_timestamp__gte=Now())

Now we thus determine the status in a passive way, which is normally more reliable than some process that actively changes it.

We can boost performance by setting a db_index=True ^[Django-doc] on it.

---

Note: It is normally better to make use of the settings.AUTH_USER_MODEL ^[Django-doc] to refer to the user model, than to use the User model ^[Django-doc] directly. For more information you can see the referencing the User model section of the documentation ^[Django-doc].