How to generate model id's with Backbone.js

Question

I am setting up the backbone sync mechanism and am a bit confused where to generate the id\'s for the models.

When I create a new model, should backbone be generating an

Answer 1

or is there some sort of mechanism where I "PUT" the data to the server, which generates the id and returns a model with the id?

Kind of. When you call the save method of your model, backbone make a POST XHR and your application server should respond with JSON contains an id. You can see an example here: http://addyosmani.com/blog/building-backbone-js-apps-with-ruby-sinatra-mongodb-and-haml/

Quoting from the link:

post '/api/:thing' do 
  # parse the post body of the content being posted, convert to a string, insert into 
  # the collection #thing and return the ObjectId as a string for reference 
  oid = DB.collection(params[:thing]).insert(JSON.parse(request.body.read.tos)) 
  "{\"id\": \"#{oid.to_s}\"}" 
end

If you don't know Ruby keep in mind what the last expression that is evaluated is automatically returned by the method.