Is there a way to refresh angular bindings using data retrieved from a getUserMedia stream?

I'm currently using getUserMedia to capture an audio stream. The audio stream is only accessible within the getUserMedia callback function. However, I have encountered an issue where Angular fails to detect changes and update the bindings when I attempt to modify them from within the callback. Despite following advice from various sources to use $scope.$apply, it doesn't seem to have any effect.

You can view my attempted solutions in this fiddle: http://jsfiddle.net/poptart911/a00koc8r/1/

    angular.module('test', [])
    .controller('mainController', function ($scope) {
    this.deviceStatus = "Angular is functioning.";
    this.deviceStatus = "Updating a binding works fine.";
    navigator.mediaDevices.getUserMedia({
        audio: true,
        video: false
    }).then(function (stream) {
        this.deviceStatus = "Angular fails to recognize this change.";
        $scope.$apply(function (stream) {
            this.deviceStatus = "I even tried $scope.apply!";
            alert("However, I am aware that this code is executing");
        });
    });
});

Answer №1

$apply function in AngularJS is functioning correctly. However, there is a scope issue with the usage of this within an inner lambda function, causing a new variable to be created instead of updating the original deviceStatus variable that is bound to the UI. To resolve this, it is recommended to store a reference to the outer this and use it within the inner lambda function when accessing deviceStatus:

angular.module('test', [])
    .controller('mainController', function ($scope) {
        var that = this;
        that.deviceStatus = "Angular is functioning properly.";
        that.deviceStatus = "Updating a binding works.";
        navigator.mediaDevices.getUserMedia({
            audio: true,
            video: false
        }).then(function (stream) {
            that.deviceStatus = "Updates in Angular are now detected correctly.";
            $scope.$apply(function (stream) {
                that.deviceStatus = "Tried using scope.apply as well!";
                alert("Executing the code successfully");
            });
       });
});

A functional jsfiddle example can be found here. For demonstration purposes, getUserMedia has been replaced with a setTimeout function.

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