I have a collection that fetches models from server.
This works, now I want to grab a model by its id with MyCollection.at(0) and I get:
MyCollection.at(0)
You can use the cid (client-side ID) attribute of the model as an argument to MyCollection.get(), which is guaranteed to exist from creation on. The documentation seems to think that will work, see http://backbonejs.org/#Collection-get.
cid
MyCollection.get()