How to define two fields "unique" as couple

django, django-models

Solution

There is a simple solution for you called unique_together which does exactly what you want.

For example:

class MyModel(models.Model):
  field1 = models.CharField(max_length=50)
  field2 = models.CharField(max_length=50)

  class Meta:
    unique_together = ('field1', 'field2',)

And in your case:

class Volume(models.Model):
  id = models.AutoField(primary_key=True)
  journal_id = models.ForeignKey(Journals, db_column='jid', null=True, verbose_name = "Journal")
  volume_number = models.CharField('Volume Number', max_length=100)
  comments = models.TextField('Comments', max_length=4000, blank=True)

  class Meta:
    unique_together = ('journal_id', 'volume_number',)

Problem

Is there a way to define a couple of fields as unique in Django? I have a table of volumes (of journals) and I don't want more then one volume number for the same journal. ``` class Volume(models.Model): id = models.AutoField(primary_key=True) journal_id = models.ForeignKey(Journals, db_column='jid', null=True, verbose_name = "Journal") volume_number = models.CharField('Volume Number', max_length=100) comments = models.TextField('Comments', max_length=4000, blank=True) ``` I tried to put `unique = True` as attribute in the fields `journal_id` and `volume_number` but it doesn't work.

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