Ember-cli , how do i change rest call on fly in the rest adapter

Im working on ember-cli, how do i change rest call on fly in the rest adapter. If i use path params not query params?for example:

export default DS.RESTAdapter.extend({   
  namespace:'res/v1/users/id',   
  pathForType: function() {  
       return Ember.String.underscore("friends");},});

Based on the user selection from dropdown we get the "id", using the id I need to get user friends from the database. Could you please suggest a better way to do. My aapplication supports pathparams not the query params