django unique together

1# Preferred alternative to unique_together, Django 2.2+
2# Use the 'constraints' var in class Meta 
3class Volume(models.Model):
4    id = models.AutoField(primary_key=True)
5    journal_id = models.ForeignKey(Journals, db_column='jid', null=True, verbose_name="Journal")
6    volume_number = models.CharField('Volume Number', max_length=100)
7    comments = models.TextField('Comments', max_length=4000, blank=True)
8
9    class Meta:
10        constraints = [
11            models.UniqueConstraint(fields=['journal_id', 'volume_number'], name='name of constraint')
12        ]

1unique_together = [['driver', 'restaurant']]
2