Historical model doesn't include fields inherited from superclass

I ran into this issue trying to add simple_history to a model using django-mptt ( https://github.com/django-mptt/django-mptt/ )

The model in question extends MPTTModel, which adds the fields lft, rght, tree_id and level to the model. However, if I try and save the model, it fails, with the exception:

TypeError: 'rght' is an invalid keyword argument for this function

I did some digging, and when the create_history_model() executes, these fields did not exist. The contents of model._meta.fields at that time was:

[<django.db.models.fields.AutoField: id>, <django.db.models.fields.CharField: name>, <django.db.models.fields.SlugField: url>, <django.db.models.fields.CharField: code>, <mptt.fields.TreeForeignKey: parent>, <django.db.models.fields.TextField: hidden_js>, <django.db.models.fields.related.ForeignKey: faculty>]

However, if I opened up a django shell, and output the contents of the same variable, I got:

[<django.db.models.fields.AutoField: id>, <django.db.models.fields.CharField: name>, <django.db.models.fields.SlugField: url>, <django.db.models.fields.CharField: code>, <mptt.fields.TreeForeignKey: parent>, <django.db.models.fields.TextField: hidden_js>, <django.db.models.fields.related.ForeignKey: faculty>, <django.db.models.fields.PositiveIntegerField: lft>, <django.db.models.fields.PositiveIntegerField: rght>, <django.db.models.fields.PositiveIntegerField: tree_id>, <django.db.models.fields.PositiveIntegerField: level>]

Which does have the additional fields. My conclusion is that the class has not yet been properly initialized at the time class_prepared is fired.

[rossmechanic]

It’s not a third party model but it’s inheriting from a third-party model. Instead of adding HistoricalRecords to the model, try adding register(ModelName) outside of the model definition (either in your models.py file or in the ready function of your AppConfig). Let me know if you run into any issues with that. @irrg

[irrg]

@rossmechanic I don’t know where my brain went on this one…that’s a super easy solution. Seems to be sticking. Will report back if anything wonky happens in relation to django-simple-history. Thanks!