Returning a object, Ember js cli

I'm pretty new to ember JS and having some issue returning a api_key object from the server on a post... I'm not sure if this is a problem with my rails serializer or a problem with the Ember itself! Any suggestions?

adapter

import DS from 'ember-data';
import Ember from 'ember';

export default DS.RESTAdapter.extend({
 host: 'http://localhost:3000',

 // =========================
 // ERROR HANDLING
 // =========================

 ajaxError: function(jsXHR) {
    var error = this._super(jsXHR);
    if (jsXHR && jsXHR.status === 422) {
        var response = Ember.$.parseJSON(jsXHR.responseText);
        var errors = {};
        if (response.errors) {
            var jsonErrors = response.errors;
            Ember.EnumerableUtils.forEach(Ember.keys(jsonErrors), function(key) {
        errors[Ember.String.camelize(key)] = jsonErrors[key];
    });
        }
        return new DS.InvalidError(errors);
    } else {
        return error;
    }
} 

});

controllers/users/new.js

import Ember from 'ember';
            import DS from 'ember-data';

            export default Ember.Controller.extend({
                actions: {
                    createUser: function() {
                        var router = this.get('target');
                        var _this = this;
                        var user = this.getProperties('name', 'email', 'username', 'password', 'password_confirmation');
                        user = this.store.createRecord('user', user);
                        user.save().then(function(apikey) {
                             ==================
                             Get ember object back with apikey attached
                             ==================
                            console.log(apikey)
                            // router.transitionTo('brands');
                        },
                        function(response) {
                            _this.set('errors', response);
                        });
                    }
                }
            });

routes/users/new.js

import Ember from 'ember';

        export default Ember.Route.extend({
            setupController: function(controller, model) {
            this.controller.set('model', this.store.createRecord('user'));
          }
        });

rails end

class UsersController < ApplicationController
before_filter :ensure_authenticated_user, only: [:index]

 def index 
    render json: User.all
 end

 def show 
    @user = User.find(params[:id])
    if @user 
        render json: @user
    else 
        render json: 'not found', status: 201
    end 
 end

 def create 
    user = User.create(user_params)
    if user.new_record?
        render json: { errors: user.errors.messages }, status: 422
    else 
        render json: { api_key: user.session_api_key }, status: 201
    end 
 end

 private 

 def user_params 
    params.require(:user).permit(:name, :username, :email, :password, :password_confirmation)
 end

end


class ApiKeySerializer < ActiveModel::Serializer
 attributes :id, :access_token
 has_one :user
end

class UserSerializer < ActiveModel::Serializer
 attributes :id, :name, :username, :email
 has_one :api_key
end