Ember data load model from DS.PromiseArray

I want to load Ember model using Ember query record.

my code:

model: function(params) {
    return this.store.find("user", {username: params.username}).then(function(result){
      return result.get('firstObject');
    });
  },

I am using ActiveModel Adapter.

In console i see "generated -> route:login Object {fullName: "route:login"}"

on debugging, I can see result.get('firstObject') is getting loaded properly but setupController is not called.