Support for relations

[HerrNiklasRaab]

The thing that keeps me from using it, is that relations like this are missing: https://docs.objectbox.io/relations

[rkistner]

This library itself is just a raw query layer for SQLite, so higher-level functionality like that is out of scope.

That said, Drift is a great persistence library that does support foreign key references, and you can use it together with sqlite_async using drift_sqlite_async.