Delaying AngularJS route change until model loaded to prevent flicker

Delaying AngularJS route change until model loaded to prevent flicker

I am wondering if there is a way (similar to Gmail) for AngularJS to delay showing a new route until after each model and its data has been fetched using its respective services.
For example, if there were a ProjectsController that listed all Projects and project_index.html which was the template that showed these Projects, Project.query() would be fetched completely before showing the new page.
Until then, the old page would still continue to show (for example, if I were browsing another page and then decided to see this Project index).

Solutions/Answers:

Solution 1:

$routeProvider resolve property allows delaying of route change until data is loaded.

First define a route with resolve attribute like this.

angular.module('phonecat', ['phonecatFilters', 'phonecatServices', 'phonecatDirectives']).
  config(['$routeProvider', function($routeProvider) {
    $routeProvider.
      when('/phones', {
        templateUrl: 'partials/phone-list.html', 
        controller: PhoneListCtrl, 
        resolve: PhoneListCtrl.resolve}).
      when('/phones/:phoneId', {
        templateUrl: 'partials/phone-detail.html', 
        controller: PhoneDetailCtrl, 
        resolve: PhoneDetailCtrl.resolve}).
      otherwise({redirectTo: '/phones'});
}]);

notice that the resolve property is defined on route.

function PhoneListCtrl($scope, phones) {
  $scope.phones = phones;
  $scope.orderProp = 'age';
}

PhoneListCtrl.resolve = {
  phones: function(Phone, $q) {
    // see: https://groups.google.com/forum/?fromgroups=#!topic/angular/DGf7yyD4Oc4
    var deferred = $q.defer();
    Phone.query(function(successData) {
            deferred.resolve(successData); 
    }, function(errorData) {
            deferred.reject(); // you could optionally pass error data here
    });
    return deferred.promise;
  },
  delay: function($q, $defer) {
    var delay = $q.defer();
    $defer(delay.resolve, 1000);
    return delay.promise;
  }
}

Notice that the controller definition contains a resolve object which declares things which should be available to the controller constructor. Here the phones is injected into the controller and it is defined in the resolve property.

The resolve.phones function is responsible for returning a promise. All of the promises are collected and the route change is delayed until after all of the promises are resolved.

Working demo: http://mhevery.github.com/angular-phonecat/app/#/phones
Source: https://github.com/mhevery/angular-phonecat/commit/ba33d3ec2d01b70eb5d3d531619bf90153496831

Solution 2:

Here’s a minimal working example which works for Angular 1.0.2

Template:

<script type="text/ng-template" id="/editor-tpl.html">
    Editor Template {{datasets}}
</script>

<div ng-view>

</div>

JavaScript:

function MyCtrl($scope, datasets) {    
    $scope.datasets = datasets;
}

MyCtrl.resolve = {
    datasets : function($q, $http) {
        var deferred = $q.defer();

        $http({method: 'GET', url: '/someUrl'})
            .success(function(data) {
                deferred.resolve(data)
            })
            .error(function(data){
                //actually you'd want deffered.reject(data) here
                //but to show what would happen on success..
                deferred.resolve("error value");
            });

        return deferred.promise;
    }
};

var myApp = angular.module('myApp', [], function($routeProvider) {
    $routeProvider.when('/', {
        templateUrl: '/editor-tpl.html',
        controller: MyCtrl,
        resolve: MyCtrl.resolve
    });
});​
​

http://jsfiddle.net/dTJ9N/3/

Streamlined version:

Since $http() already returns a promise (aka deferred), we actually don’t need to create our own. So we can simplify MyCtrl. resolve to:

MyCtrl.resolve = {
    datasets : function($http) {
        return $http({
            method: 'GET', 
            url: 'http://fiddle.jshell.net/'
        });
    }
};

The result of $http() contains data, status, headers and config objects, so we need to change the body of MyCtrl to:

$scope.datasets = datasets.data;

http://jsfiddle.net/dTJ9N/5/

Solution 3:

I see some people asking how to do this using the angular.controller method with minification friendly dependency injection. Since I just got this working I felt obliged to come back and help. Here’s my solution (adopted from the original question and Misko’s answer):

angular.module('phonecat', ['phonecatFilters', 'phonecatServices', 'phonecatDirectives']).
  config(['$routeProvider', function($routeProvider) {
    $routeProvider.
      when('/phones', {
        templateUrl: 'partials/phone-list.html', 
        controller: PhoneListCtrl, 
        resolve: { 
            phones: ["Phone", "$q", function(Phone, $q) {
                var deferred = $q.defer();
                Phone.query(function(successData) {
                  deferred.resolve(successData); 
                }, function(errorData) {
                  deferred.reject(); // you could optionally pass error data here
                });
                return deferred.promise;
             ]
            },
            delay: ["$q","$defer", function($q, $defer) {
               var delay = $q.defer();
               $defer(delay.resolve, 1000);
               return delay.promise;
              }
            ]
        },

        }).
      when('/phones/:phoneId', {
        templateUrl: 'partials/phone-detail.html', 
        controller: PhoneDetailCtrl, 
        resolve: PhoneDetailCtrl.resolve}).
      otherwise({redirectTo: '/phones'});
}]);

angular.controller("PhoneListCtrl", [ "$scope", "phones", ($scope, phones) {
  $scope.phones = phones;
  $scope.orderProp = 'age';
}]);

Since this code is derived from the question/most popular answer it is untested, but it should send you in the right direction if you already understand how to make minification friendly angular code. The one part that my own code didn’t requires was an injection of “Phone” into the resolve function for ‘phones’, nor did I use any ‘delay’ object at all.

I also recommend this youtube video http://www.youtube.com/watch?v=P6KITGRQujQ&list=UUKW92i7iQFuNILqQOUOCrFw&index=4&feature=plcp , which helped me quite a bit

Should it interest you I’ve decided to also paste my own code (Written in coffeescript) so you can see how I got it working.

FYI, in advance I use a generic controller that helps me do CRUD on several models:

appModule.config ['$routeProvider', ($routeProvider) ->
  genericControllers = ["boards","teachers","classrooms","students"]
  for controllerName in genericControllers
    $routeProvider
      .when "/#{controllerName}/",
        action: 'confirmLogin'
        controller: 'GenericController'
        controllerName: controllerName
        templateUrl: "/static/templates/#{controllerName}.html"
        resolve:
          items : ["$q", "$route", "$http", ($q, $route, $http) ->
             deferred = $q.defer()
             controllerName = $route.current.controllerName
             $http(
               method: "GET"
               url: "/api/#{controllerName}/"
             )
             .success (response) ->
               deferred.resolve(response.payload)
             .error (response) ->
               deferred.reject(response.message)

             return deferred.promise
          ]

  $routeProvider
    .otherwise
      redirectTo: '/'
      action: 'checkStatus'
]

appModule.controller "GenericController", ["$scope", "$route", "$http", "$cookies", "items", ($scope, $route, $http, $cookies, items) ->

  $scope.items = items
      #etc ....
    ]

Solution 4:

This commit, which is part of version 1.1.5 and above, exposes the $promise object of $resource. Versions of ngResource including this commit allow resolving resources like this:

$routeProvider

resolve: {
    data: function(Resource) {
        return Resource.get().$promise;
    }
}

controller

app.controller('ResourceCtrl', ['$scope', 'data', function($scope, data) {

    $scope.data = data;

}]);

Solution 5:

This snippet is dependency injection friendly (I even use it in combination of ngmin and uglify) and it’s a more elegant domain driven based solution.

The example below registers a Phone resource and a constant phoneRoutes, which contains all your routing information for that (phone) domain. Something I didn’t like in the provided answer was the location of the resolve logic — the main module should not know anything or be bothered about the way the resource arguments are provided to the controller. This way the logic stays in the same domain.

Note: if you’re using ngmin (and if you’re not: you should) you only have to write the resolve functions with the DI array convention.

angular.module('myApp').factory('Phone',function ($resource) {
  return $resource('/api/phone/:id', {id: '@id'});
}).constant('phoneRoutes', {
    '/phone': {
      templateUrl: 'app/phone/index.tmpl.html',
      controller: 'PhoneIndexController'
    },
    '/phone/create': {
      templateUrl: 'app/phone/edit.tmpl.html',
      controller: 'PhoneEditController',
      resolve: {
        phone: ['$route', 'Phone', function ($route, Phone) {
          return new Phone();
        }]
      }
    },
    '/phone/edit/:id': {
      templateUrl: 'app/phone/edit.tmpl.html',
      controller: 'PhoneEditController',
      resolve: {
        form: ['$route', 'Phone', function ($route, Phone) {
          return Phone.get({ id: $route.current.params.id }).$promise;
        }]
      }
    }
  });

The next piece is injecting the routing data when the module is in the configure state and applying it to the $routeProvider.

angular.module('myApp').config(function ($routeProvider, 
                                         phoneRoutes, 
                                         /* ... otherRoutes ... */) {

  $routeProvider.when('/', { templateUrl: 'app/main/index.tmpl.html' });

  // Loop through all paths provided by the injected route data.

  angular.forEach(phoneRoutes, function(routeData, path) {
    $routeProvider.when(path, routeData);
  });

  $routeProvider.otherwise({ redirectTo: '/' });

});

Testing the route configuration with this setup is also pretty easy:

describe('phoneRoutes', function() {

  it('should match route configuration', function() {

    module('myApp');

    // Mock the Phone resource
    function PhoneMock() {}
    PhoneMock.get = function() { return {}; };

    module(function($provide) {
      $provide.value('Phone', FormMock);
    });

    inject(function($route, $location, $rootScope, phoneRoutes) {
      angular.forEach(phoneRoutes, function (routeData, path) {

        $location.path(path);
        $rootScope.$digest();

        expect($route.current.templateUrl).toBe(routeData.templateUrl);
        expect($route.current.controller).toBe(routeData.controller);
      });
    });
  });
});

You can see it in full glory in my latest (upcoming) experiment.
Although this method works fine for me, I really wonder why the $injector isn’t delaying construction of anything when it detects injection of anything that is a promise object; it would make things soooOOOOOooOOOOO much easier.

Edit: used Angular v1.2(rc2)

Solution 6:

Delaying showing the route is sure to lead to an asynchronous tangle… why not simply track the loading status of your main entity and use that in the view. For example in your controller you might use both the success and error callbacks on ngResource:

$scope.httpStatus = 0; // in progress
$scope.projects = $resource.query('/projects', function() {
    $scope.httpStatus = 200;
  }, function(response) {
    $scope.httpStatus = response.status;
  });

Then in the view you could do whatever:

<div ng-show="httpStatus == 0">
    Loading
</div>
<div ng-show="httpStatus == 200">
    Real stuff
    <div ng-repeat="project in projects">
         ...
    </div>
</div>
<div ng-show="httpStatus >= 400">
    Error, not found, etc. Could distinguish 4xx not found from 
    5xx server error even.
</div>