Doctrine inheritance strategy when two different subclasses extend the same entity instance

Question

I am developing an application for managing court interpreter services (using Doctrine and Zend Framework 2). There are a lot of people involved who have various specialized roles, hence a Person superclass, and subclasses. The class hierarchy is not complicated in a vertical sense -- one generation of inheritance is enough -- but the horizontal aspect is giving me trouble.

I don't think mapped superclasses fit my case. I also considered single-table inheritance but that would quickly get ugly because the subclasses have their own entity relationships, too much stuff to cram gracefully into a single table.

That leaves us with class table inheritance, which is a really nice fit in most respects, but... I will have plenty of cases where the subclass User (for authentication) and the subclass Interpreter will (or should) point to the same row in the parent data table, because they represent one and the same person in reality. But because of the discriminator column you have to choose one or the other, or else create two different rows holding the same data -- and the normalization police should get you for that.

I think maybe either the User or the Interpreter entity has to simply have a one-to-one relationship with the Person entity, and deal with that semi-manually. Another option I suppose would be to collapse User into Person -- but that's ugly because a lot of people will not be authenticating and will not have or need a password. I have looked at Doctrine inheritance, several entities extending the same super class and How to change and entity type in Doctrine2 CTI Inheritance (inter alia) and neither one solves this.

So, I wonder if anyone has any suggestions. Thanks.

Answer 1

It sounds like you're managing a bunch of data about Persons, which identifies individual humans in the world. Since only some subset of the people in the system are Users, I'd argue that concerns about authentication, audit logging, notifications, etc are separate from the concerns of the Person class hierarchy.

I'd advise removing User from the Person class hierarchy. Perhaps rename it Account, to make it feel less person-y. An Account can have an owner property, which is a relation to Person. If you want to use the Person's email address as an identifier for authentication, that's fine. If you later wanted to add a username instead, that would be a property of Account, since it's only meaningful in that context.