regluit/booxtream/models.py

from datetime import timedelta, datetime

from django.db import models

class Boox(models.Model):
    """
    keeps a record of a file that's been watermarked
    """
    download_link_epub = models.URLField(null=True)
    download_link_mobi = models.URLField(null=True)
    referenceid = models.CharField(max_length=32)
    downloads_remaining = models.PositiveSmallIntegerField(default=0)
    expirydays = models.PositiveSmallIntegerField()
    created = models.DateTimeField(auto_now_add=True)

    @property
    def expired(self):
        return self.created+timedelta(days=self.expirydays) < datetime.now()

    def download_link(self, format):
        if format == 'epub':
            return self.download_link_epub
        elif  format == 'mobi':
            return self.download_link_mobi
        return None