[AngularJS] Best Practise - Resolve promises in router, defer controllers

See more:http://toddmotto.com/opinionated-angular-js-styleguide-for-teams/

/**
 * Created by Answer1215 on 1/13/2015.
 */

/**
*  Controller(s)
* */

 function AppController($rootScope, $location) {

    var appCtrl = this;

    $rootScope.$on('$routeChangeError', function(event, current, previous, rejection) {
        appCtrl.message = rejection.message;
        appCtrl.isError = true;
    })

    appCtrl.goHome = function() {

        $location.path('/');
    }
}

/**
 *  Directive(s)
 * */

function ErrorDirective() {
    return {
        restrict: "EA",
        bindToController: true,
        controller: 'AppController',
        controllerAs: 'appCtrl',
        templateUrl: 'error.html'
    }
}

/**
 *  Angular module
 * */

 angular.module('app', [
    'ngRoute',
    'app.home'
])
    .constant('PEOPLE_URL', 'data.json')
    .controller('AppController', AppController)
    .directive('error', ErrorDirective)
    .config(function($routeProvider) {
        $routeProvider
            .when('/', {
                templateUrl: "home.html",
                controller: "HomeController",
                controllerAs: "homeCtrl",
                /*
                *  resolve run first, prepare the data ready,
                *  then controller & template show up
                * */
                resolve: HomeController.resolve
            });
    });

/**
 * Created by Answer1215 on 1/13/2015.
 */

function HomeController(loadPeople, getMessage) {
    var homeCtrl = this;

    homeCtrl.message = getMessage;
    homeCtrl.people = loadPeople;
}

HomeController.resolve = {

    loadPeople: function(SimpleDataService) {
        return SimpleDataService.getPeople();
    },
    getMessage : function(SimpleDataService) {
        return SimpleDataService.message;
    }
}

function SimpleDataService($http, $q, PEOPLE_URL) {
    var simpleData = {};
    simpleData.people = [];
    simpleData.message = "Hello From Service";

    simpleData.getPeople = function() {
        return fetchPeople().then(function(result) {
            return result.data;
        });

    }

    function fetchPeople() {
        var defer = $q.defer();
        $http.get(PEOPLE_URL)
           .success(function(data, status, headers, config) {
               simpleData.people = data;
               defer.resolve({data: data, message: "OK"});
            }).
            error(function(data, status, headers, config) {

               if(status === 404){
                   data =  data;
                   defer.reject({data: data, message: "Cannot find " + config.url});
               }
            });
        return defer.promise;
    }

    return simpleData;
}

angular.module('app.home', [])
    .controller('HomeController',  HomeController)
    .service('SimpleDataService', SimpleDataService);

While the routes are being resolved we want to show the user something to indicate progress. Angular will fire the $routeChangeStart event as we navigate away from the page, which we can show some form of loading and ajax spinner, which can then be removed on the $routeChangeSuccess