Custom field with default unique

[petrprikryl]

Example:

class UniqueField(models.CharField):
    def __init__(self, *args, **kwargs):
        kwargs.setdefault("unique", True)
        super().__init__(*args, **kwargs)


@pghistory.track()
class Foo(models.Model):
    slug = UniqueField()

Which leads to following migration:

        migrations.CreateModel(
            name='Foo',
            fields=[
                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
                ('slug', foo_app.models.UniqueField(unique=True)),
            ],
        ),
        migrations.CreateModel(
            name='FooEvent',
            fields=[
                ('pgh_id', models.AutoField(primary_key=True, serialize=False)),
                ('pgh_created_at', models.DateTimeField(auto_now_add=True)),
                ('pgh_label', models.TextField(help_text='The event label.')),
                ('id', models.IntegerField()),
                ('slug', foo_app.models.UniqueField(unique=True)),
            ],
            options={
                'abstract': False,
            },
        ),

I think that FooEvent shouldn't have slug field with unique constraint as it prevents multiple tracking events for same Foo record.

Next, it is working correctly for plain CharField with explicit unique=True (constraint is not present in the event model). The problem seems to be custom fields with implicit defaults which deviates from Django's defaults.

Thanks for any opinion to this topic.

[wesleykendall]

Yea, seems like pghistory does not work well with custom fields like this.

The workaround for now is to declare a custom event model https://django-pghistory.readthedocs.io/en/3.5.1/event_models/#custom-event-models and explicitly declare the field

Will leave this open as a known bug. I imagine the solution may be straightforward if someone wants to try to address it. I wont be able to get to this anytime soon