What options are there for mapping relationships in Models/Entities

This has been on my mind as well.

I did a search through Packagist and came across this: github.com/4spacesdk/CI4OrmExtension This seems like a great tool and has all the features you would need to maintain relationships between entities.

It kind mimics another great CI3 ORM tool written by Nick Tsai that you can find here: https://github.com/yidas/codeigniter-model

My favourite feature of both of these is that each entity has a built in $entity->save() function rather than having to load the model and pass the entity to save.