documentcloud/backbone — pull request #1558 by caseywebdev (2012-08-17 15:38:15+00:00)
Title: Added support for composite keys as the `idAttribute`

I like to create Backbone models for my join tables, but I don't want to throw an unnecessary `id` field in the table when a composite key is ideal. This commit makes it possible to set `idAttribute` to an array of attribute names. See the tests for examples. Please let me know if there is a case where this breaks, but all tests passing so far.