问题
I'm trying to model a schema where a list can have many items and each item can belong to many lists. It's clear to me that I can have a :list/items ref type to model the relationship, but I'd like to also have a rank attribute which determines an item's position in each list where it exists. How might one do such a thing?
回答1:
The only answer I have - assuming that positioning is list dependent - is that you need to add an indirecting entity with a rank attribute. This isn't very pleasant. It would be nice if a many relation could be ordered, as this use case would simplify substantially.
来源：https://stackoverflow.com/questions/33682064/properties-on-datomic-ref-relationships