构建Rails和Backbone.js模型之间的多对多关系

I'm trying to set up an item model and a tag model that have a many-to-many relationship (items have multiple tags and tags belong to multiple items). I'm using Rails and Backbone.js, so I need to have them store, retrieve and update models seamlessly between each other. I would also love it if I could save a new list of tags for a specific item in one go from the client. mo