+
+
+class MediaInsertSet(models.Model):
+ file_format = models.CharField(max_length=8, choices=[
+ ('epub', 'epub'),
+ ('mobi', 'mobi'),
+ ('pdf', 'pdf'),
+ ])
+ etag = models.CharField(max_length=64, blank=True)
+
+ def update_etag(self):
+ self.etag = hashlib.sha1(json.dumps(self.get_texts()).encode('utf-8')).hexdigest()
+ self.save(update_fields=['etag'])
+
+ def get_texts(self):
+ return [t.text for t in self.mediainserttext_set.all()]
+
+ @classmethod
+ def get_for_format(cls, file_format):
+ return cls.objects.filter(file_format=file_format).first()
+
+ @classmethod
+ def get_texts_for(cls, file_format):
+ self = cls.get_for_format(file_format)
+ if self is None:
+ return []
+ return self.get_texts()
+
+
+class MediaInsertText(models.Model):
+ media_insert_set = models.ForeignKey(MediaInsertSet, models.CASCADE)
+ ordering = models.IntegerField()
+ text = models.TextField()
+
+ class Meta:
+ ordering = ('ordering',)
+
+
+from django.db.models.signals import post_save, post_delete
+from django.dispatch import receiver
+
+@receiver(post_delete, sender=MediaInsertText)
+@receiver(post_save, sender=MediaInsertText)
+def update_etag(sender, instance, **kwargs):
+ instance.media_insert_set.update_etag()