Unique fields that allow nulls in Django

Question

I have model Foo which has field bar. The bar field should be unique, but allow nulls in it, meaning I want to allow more than one record if bar field is null,

Answer 1

If you have a model MyModel and want my_field to be Null or unique, you can override model's save method:

class MyModel(models.Model):
    my_field = models.TextField(unique=True, default=None, null=True, blank=True) 

    def save(self, **kwargs):
        self.my_field = self.my_field or None
        super().save(**kwargs)

This way, the field cannot be blank will only be non-blank or null. nulls do not contradict uniqueness