Angular parent scope does not reflect changes when a directive updates the shared scope variable

Question

Angular parent scope does not reflect changes when a directive updates the shared scope variable

My directive is designed to validate and modify a specific binded value before triggering the button action. However, I am facing an issue where any updates made to the directive value are not being reflected in the parent scope. Even though I have used (=) in the directive, which should theoretically update the parent scope.

I would appreciate any insights on what might be causing this problem. Attached are some images for reference.

In the view where both the parent and the directive share the same text value,

The modified value assigned during validation does not appear in the selected node of the parent when the function is executed. Nonetheless, I can see the updated value in the text area, albeit it doesn't carry over to the parent when the function runs.

Despite attempting solutions like $timeout and $evalAsync on the scope.ngClick, I haven't had any success in resolving this issue.

javascript angularjs

Answer 1

Answer №1

If changes are made within event handlers of custom directives, Angular's digest cycle may not be triggered automatically. To ensure that the scope changes are recognized by Angular, you can manually notify it by calling scope.$digest() or scope.$apply(). Additionally, I have observed that the method ok() is being called twice: once within Angular's ngClick directive and again within your directive. If this behavior is unintended, consider removing one of the calls from your directive implementation. Here is a snippet of working code:

HTML

<body ng-controller="myController">
  <textarea ng-model="selected.note"></textarea>
  <button type="button" validatetext="selected.note" ng-click="ok()">Click Me!</button>
</body>

JavaScript

angular.module('online-desktop', []).
  controller('myController', ['$scope', function($scope) {
    $scope.selected = {
      note: 'old value'
    };
    $scope.ok = function() {
      alert($scope.selected.note);
    };
  }]).
  directive('validatetext', [function() {
    return {
      scope: {
        validatetext: '='
      },
      link: function(scope, element, attr) {
        element.on('click', function() {
          scope.$apply(function() { // <= Ensure changes are made within $apply()
            scope.validatetext = 'some new value';
          });
        });
      }
    }
  }]);

Plunker Example: http://plnkr.co/edit/rmJVBzjIeiVcoQUV79z2?p=preview

Answer 2

If changes are made within event handlers of custom directives, Angular's digest cycle may not be triggered automatically. To ensure that the scope changes are recognized by Angular, you can manually notify it by calling scope.$digest() or scope.$apply(). Additionally, I have observed that the method ok() is being called twice: once within Angular's ngClick directive and again within your directive. If this behavior is unintended, consider removing one of the calls from your directive implementation. Here is a snippet of working code:

HTML

<body ng-controller="myController">
  <textarea ng-model="selected.note"></textarea>
  <button type="button" validatetext="selected.note" ng-click="ok()">Click Me!</button>
</body>

JavaScript

angular.module('online-desktop', []).
  controller('myController', ['$scope', function($scope) {
    $scope.selected = {
      note: 'old value'
    };
    $scope.ok = function() {
      alert($scope.selected.note);
    };
  }]).
  directive('validatetext', [function() {
    return {
      scope: {
        validatetext: '='
      },
      link: function(scope, element, attr) {
        element.on('click', function() {
          scope.$apply(function() { // <= Ensure changes are made within $apply()
            scope.validatetext = 'some new value';
          });
        });
      }
    }
  }]);

Plunker Example: http://plnkr.co/edit/rmJVBzjIeiVcoQUV79z2?p=preview

Answer 3

Answer №2

One recommendation is to experiment with triggering a $rootScope.$broadcast from the directive and handling it in the parent component using $scope.$on

//directive
$rootScope.$broadcast("dataChanged", newData);

//parent
$scope.$on("dataChanged", function(event, newData){
//perform necessary updates here
});

Another option to consider is utilizing $scope.$emit instead of $rootScope.$broadcast.

Answer 4

One recommendation is to experiment with triggering a $rootScope.$broadcast from the directive and handling it in the parent component using $scope.$on

//directive
$rootScope.$broadcast("dataChanged", newData);

//parent
$scope.$on("dataChanged", function(event, newData){
//perform necessary updates here
});

Another option to consider is utilizing $scope.$emit instead of $rootScope.$broadcast.

Angular parent scope does not reflect changes when a directive updates the shared scope variable

Answer №1

Answer №2

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