DataMapper ORM v1.8.2

[eluser]WanWizard[/eluser]
There's a bit more info on advanced relations here, with a discussion I think is relevant in this case.

One of the issues is that Datamapper always needs both sides of the relation, they have to be symmetrical. So the user model needs two has_many definitions, that have to point back to the admin and publisher definitions on the materials model. If those are missing several types of query will fail.

So instead of the current 'material' relation you need the relation 'publishes' (which links to the publisher_id relation) and 'administers' (which links to the admin_id relation).

I'll see if I can come of with a more elaborate example for the docs.