Delaying AngularJS route change until model loaded to prevent flicker

Question

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 it

Answer 1

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/

Answer 2

I worked from Misko's code above and this is what I've done with it. This is a more current solution since $defer has been changed to $timeout. Substituting $timeout however will wait for the timeout period (in Misko's code, 1 second), then return the data hoping it's resolved in time. With this way, it returns asap.

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

PhoneListCtrl.resolve = {

  phones: function($q, Phone) {
    var deferred = $q.defer();

    Phone.query(function(phones) {
        deferred.resolve(phones);
    });

    return deferred.promise;
  }
}

Answer 3

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)

Answer 4

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 ....
    ]

Answer 5

You can use $routeProvider resolve property to delay route change until data is loaded.

angular.module('app', ['ngRoute']).
  config(['$routeProvider', function($routeProvider, EntitiesCtrlResolve, EntityCtrlResolve) {
    $routeProvider.
      when('/entities', {
        templateUrl: 'entities.html', 
        controller: 'EntitiesCtrl', 
        resolve: EntitiesCtrlResolve
      }).
      when('/entity/:entityId', {
        templateUrl: 'entity.html', 
        controller: 'EntityCtrl', 
        resolve: EntityCtrlResolve
      }).
      otherwise({redirectTo: '/entities'});
}]);

Notice that the resolve property is defined on route.

EntitiesCtrlResolve and EntityCtrlResolve is constant objects defined in same file as EntitiesCtrl and EntityCtrl controllers.

// EntitiesCtrl.js

angular.module('app').constant('EntitiesCtrlResolve', {
  Entities: function(EntitiesService) {
    return EntitiesService.getAll();
  }
});

angular.module('app').controller('EntitiesCtrl', function(Entities) {
  $scope.entities = Entities;

  // some code..
});

// EntityCtrl.js

angular.module('app').constant('EntityCtrlResolve', {
  Entity: function($route, EntitiesService) {
    return EntitiesService.getById($route.current.params.projectId);
  }
});

angular.module('app').controller('EntityCtrl', function(Entity) {
  $scope.entity = Entity;

  // some code..
});

Answer 6

I like darkporter's idea because it will be easy for a dev team new to AngularJS to understand and worked straight away.

I created this adaptation which uses 2 divs, one for loader bar and another for actual content displayed after data is loaded. Error handling would be done elsewhere.

Add a 'ready' flag to $scope:

$http({method: 'GET', url: '...'}).
    success(function(data, status, headers, config) {
        $scope.dataForView = data;      
        $scope.ready = true;  // <-- set true after loaded
    })
});

In html view:

<div ng-show="!ready">

    <!-- Show loading graphic, e.g. Twitter Boostrap progress bar -->
    <div class="progress progress-striped active">
        <div class="bar" style="width: 100%;"></div>
    </div>

</div>

<div ng-show="ready">

    <!-- Real content goes here and will appear after loading -->

</div>

See also: Boostrap progress bar docs