Utilizing AngularJS to Bind a Dynamic Service Value to Scope Data

Question

Utilizing AngularJS to Bind a Dynamic Service Value to Scope Data

My factory manages a collection that is constantly updated with new values from socket.io. I want to update a scope variable with this collection in real-time without using callbacks in the controller. Ideally, I would like to achieve this behavior similar to when using defer.resolve(collection). Although I could use defer.notify(collection), it leads to messy code like:

service.update().then(null, null, function(collection){
    $scope.collection = collection()
}

This approach seems quite cumbersome. If I use promise resolve, I can simply do:

$scope.collection = service.collection()

However, this only updates the service once. How can I accomplish continuous updates using promises or another technique?

javascript angularjs socket.io promise q

Answer 1

Answer №1

Since version 1.2.0-rc.3, Angular no longer automatically unwraps promises. Some may find this change unattractive, but personally, I don't see any issues with it.

If your service is asynchronous and returns a promise like the following:

app.factory('service', function ($http, $q) { 

    return{
        update: function () { 

            var deferred = $q.defer();

           //....
           .success(function (data) {
                      deferred.resolve(data);
                }).error(function() {
                deferred.reject("An error occurred.");
            });
            //Returning the promise object
            return deferred.promise;
        }
    };
});

The controller implementation will be as follows:

service.update()   // returns a promise
       .then(function (result) {
          //.....                          
         }, function (result) {
           alert("Error: No data was returned");
          });

Answer 2

Since version 1.2.0-rc.3, Angular no longer automatically unwraps promises. Some may find this change unattractive, but personally, I don't see any issues with it.

If your service is asynchronous and returns a promise like the following:

app.factory('service', function ($http, $q) { 

    return{
        update: function () { 

            var deferred = $q.defer();

           //....
           .success(function (data) {
                      deferred.resolve(data);
                }).error(function() {
                deferred.reject("An error occurred.");
            });
            //Returning the promise object
            return deferred.promise;
        }
    };
});

The controller implementation will be as follows:

service.update()   // returns a promise
       .then(function (result) {
          //.....                          
         }, function (result) {
           alert("Error: No data was returned");
          });

Answer 3

Answer №2

To handle this situation, you can utilize the $broadcast method. Simply have your service update the collection and then trigger it using:

$rootScope.$broadcast('collectionUpdated');

Next, in the controller, listen for the event like so:

$scope.$on('collectionUpdated', _updateCollection);
function _updateCollection() {
    $scope.collection = Service.collection;
}

Answer 4

To handle this situation, you can utilize the $broadcast method. Simply have your service update the collection and then trigger it using:

$rootScope.$broadcast('collectionUpdated');

Next, in the controller, listen for the event like so:

$scope.$on('collectionUpdated', _updateCollection);
function _updateCollection() {
    $scope.collection = Service.collection;
}

Utilizing AngularJS to Bind a Dynamic Service Value to Scope Data

Answer №1

Answer №2

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