How can I use a deffered promise to call a method on the second controller from the first controller in AngularJS and Ionic?

Question

How can I use a deffered promise to call a method on the second controller from the first controller in AngularJS and Ionic?

I am facing a challenge where I need to initialize user setting values (which are set to rootscope) from the second controller's method in the first controller.

Once the values are successfully set to rootscope, I need to return a premise and continue executing the second method of the first controller.

I have tried using emit and broadcast examples, but haven't had any luck so far.

Can someone please provide advice on how to accomplish this correctly?

I'm working with Angular 1.2 and Ionic 1, beta 13

Thank you in advance for any assistance.

Template:

<ion-view title="{{ 'DAYS_RESULTS' | translate }}" >
    <ion-content ng-controller="DailyStatsCtrl" ng-init="setData()">

Code:

// First cotroller call setData in ng-init

angular.module('starter')
// Controller definition
.controller('DailyStatsCtrl', function($scope, $rootScope, $ionicSlideBoxDelegate, $timeout , $ionicLoading , $q, $translate, DialsComputeService, cordova, LocalStorService,  $ionicPopup, $state, $ionicNavBarDelegate, testService, $ionicPlatform) {


        $scope.setData = function() {
            $ionicPlatform.ready(function() {
                $timeout(function() {
                    $scope.$emit("onSomething", "");
                    alert("TEST");
                }, 1000);
            });
        };

In the second controller:

angular.module('starter')
// Controller definition
.controller('SettingsCtrl', function($scope, $rootScope, $ionicLoading, $ionicPlatform, LocalStorService, $timeout, $translate, $ionicPopup, $state, $ionicNavBarDelegate) {

    $scope.getUserSettigns = function() {
        alert("received");
        $scope.test = 'event received';
    }
    $scope.$on('onSomething', function(e) {
        $scope.getUserSettigns();
    });

javascript angularjs angular-promise rootscope emit

Answer 1

Answer №1

When working with Ionic, it's important to note that a controller function cannot be called before the view of the controller has finished loading. If you need to ensure that your second controller's view has been loaded before executing a function, you can follow these steps:

secondview.html:

Assign an ID to the ion-content element in order to access the controller scope:

<ion-view title="second">
    <ion-content id="secondView">

    </ion-content>
</ion-view>

Second controller:

app.controller('SecondController', function($scope, $http) {

    $scope.someFunction = function(args) {
        alert(args.Message);
    };

});

Code:

app.controller('CodeController', function($scope) {

    $scope.$on('$ionicView.beforeEnter', function(){
        angular.element($('#secondView')).scope().someFunction({ Message: "Hello!" });
    });

});

I hope this explanation helps clarify any confusion.

Answer 2

When working with Ionic, it's important to note that a controller function cannot be called before the view of the controller has finished loading. If you need to ensure that your second controller's view has been loaded before executing a function, you can follow these steps:

secondview.html:

Assign an ID to the ion-content element in order to access the controller scope:

<ion-view title="second">
    <ion-content id="secondView">

    </ion-content>
</ion-view>

Second controller:

app.controller('SecondController', function($scope, $http) {

    $scope.someFunction = function(args) {
        alert(args.Message);
    };

});

Code:

app.controller('CodeController', function($scope) {

    $scope.$on('$ionicView.beforeEnter', function(){
        angular.element($('#secondView')).scope().someFunction({ Message: "Hello!" });
    });

});

I hope this explanation helps clarify any confusion.

Answer 3

Answer №2

To achieve the desired outcome, utilizing $rootScope is not necessary (though it can be used). The use of $broadcast will activate watchers for events in the current scope and all descendant scopes. For instance, the following code in the parent controller:

$scope.setData = function() {
    $timeout(function() {
      $scope.$broadcast("onSomething", "");
    }, 5000); 
  };

will invoke any defined $scope.$on('onSomething', ..) callbacks in both the current and descendant controllers.

For a demonstration with a live example, please refer to this CodePen link where the text 'event received' will be displayed after 5 seconds in the rendered HTML.

http://codepen.io/anon/pen/VYeEOg

Answer 4

To achieve the desired outcome, utilizing $rootScope is not necessary (though it can be used). The use of $broadcast will activate watchers for events in the current scope and all descendant scopes. For instance, the following code in the parent controller:

$scope.setData = function() {
    $timeout(function() {
      $scope.$broadcast("onSomething", "");
    }, 5000); 
  };

will invoke any defined $scope.$on('onSomething', ..) callbacks in both the current and descendant controllers.

For a demonstration with a live example, please refer to this CodePen link where the text 'event received' will be displayed after 5 seconds in the rendered HTML.

http://codepen.io/anon/pen/VYeEOg

Answer 5

Answer №3

Recently, I had the opportunity to dive into event emitting functionality within my code. It may seem like a hassle at first, but here's a brief overview:

$scope.$broadcast

This method is used to send events down to child scopes in the application.

According to the Angular documentation:

Dispatches an event name downwards to all child scopes (and their children)

$scope.$emit

On the other hand, this function sends events up to parent scopes.

As per the Angular documentation:

Dispatches an event name upwards through the scope hierarchy

My colleague and I strongly believe that using the $broadcast method is the most effective approach. To ensure reliability, we recommend injecting $rootScope in the controller or service responsible for dispatching the event and then using $broadcast as shown below:

.service('DispatchEvent', ['$rootScope', function ($rootScope) {
    $rootScope.$broadcast('someEvent');
}]);

For the controller or service handling the received event, inject $scope and employ $on as follows:

.controller('ReceivingEventsController', ['$scope', function ($scope) { 
     $scope.$on('someEvent', function (e) { 
         // do something 
     }); 
}]);

By following this approach, the $rootScope will consistently broadcast down the scope hierarchy, relieving the need to deliberate between $emit and $broadcast. Utilizing $scope ensures it will always be a child of $rootScope.

Applying this concept to your situation is straightforward. Inject $rootScope and utilize $broadcast in the first controller, while inject $scope and use $on in the second controller, similar to the example below:

$scope.$on('onSomething', function(e) {
    $scope.getUserSettings();
});

To see a demonstration, check out this functional plunker: http://plnkr.co/edit/PrD3vB80lFSt0a9WQLJ9?p=preview

Answer 6

Recently, I had the opportunity to dive into event emitting functionality within my code. It may seem like a hassle at first, but here's a brief overview:

$scope.$broadcast

This method is used to send events down to child scopes in the application.

According to the Angular documentation:

Dispatches an event name downwards to all child scopes (and their children)

$scope.$emit

On the other hand, this function sends events up to parent scopes.

As per the Angular documentation:

Dispatches an event name upwards through the scope hierarchy

My colleague and I strongly believe that using the $broadcast method is the most effective approach. To ensure reliability, we recommend injecting $rootScope in the controller or service responsible for dispatching the event and then using $broadcast as shown below:

.service('DispatchEvent', ['$rootScope', function ($rootScope) {
    $rootScope.$broadcast('someEvent');
}]);

For the controller or service handling the received event, inject $scope and employ $on as follows:

.controller('ReceivingEventsController', ['$scope', function ($scope) { 
     $scope.$on('someEvent', function (e) { 
         // do something 
     }); 
}]);

By following this approach, the $rootScope will consistently broadcast down the scope hierarchy, relieving the need to deliberate between $emit and $broadcast. Utilizing $scope ensures it will always be a child of $rootScope.

Applying this concept to your situation is straightforward. Inject $rootScope and utilize $broadcast in the first controller, while inject $scope and use $on in the second controller, similar to the example below:

$scope.$on('onSomething', function(e) {
    $scope.getUserSettings();
});

To see a demonstration, check out this functional plunker: http://plnkr.co/edit/PrD3vB80lFSt0a9WQLJ9?p=preview

How can I use a deffered promise to call a method on the second controller from the first controller in AngularJS and Ionic?

Answer №1

Answer №2

Answer №3

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