In my app, everything I do with data is based on the primary key as the data is stored in the database. I would like to grab a model from a collection based on this key.
Take a look at the get method, it may be of some help :)
http://backbonejs.org/#Collection-get
get collection.get(id) Get a model from a collection, specified by an id, a cid, or by passing in a model.