Updating parent scope data from within a directive without relying on isolated scope bindings

Question

Updating parent scope data from within a directive without relying on isolated scope bindings

What is the best method for passing data back to the parent scope in AngularJS without using isolated scopes?

Imagine I have a directive called x, and I want to access its value named a. The desired syntax would be:

<x a="some.obj.myA"></x>
current a: {{some.obj.myA}}

To implement the x directive, I would do the following:

app.directive('x', function() {
    var a = {};
    return {
        restrict: 'E',
        link: function($scope, $element, $attrs) {
            var parentExpression = $attrs.a;

            // ???
        },
        replace: true,
        template: ...
    };
});

Essentially, my goal is to always ensure that "$scope.$parent[parentExpression]" (pseudo code) remains equal to the local variable a's value. This should work seamlessly even if parentExpression points to a complex nested object, array, or any other assignable expression.

How can I achieve this functionality?

javascript angularjs data-binding

Answer 1

Answer №1

Various ways to implement:

Utilizing ng-model

For instance:

app.directive('x', function() {
  var a = {};
  return {
    require:'ngModel',
    restrict: 'E',
    link: function($scope, $element, $attrs, ctrl) {
       var currentValue = ctrl.$viewValue;
       //... manipulate the value and update
       ctrl.$setViewValue(newValue);
       ctrl.$render();
    },
    replace: true,
    template: ...
  };
});

<x ng-model="some.obj.myA"></x>

If your directive intends to modify the modal's value, consider exploring $formatters/$parsers. Also, refer to $viewChangeListeners for observing view value changes.

 angular.module('app', []).directive('x', function() {
   var a = {};
   return {
     require: 'ngModel',
     restrict: 'E',
     link: function($scope, $element, $attrs, ctrl) {
       //override render function
       ctrl.$render = function() {
         var currentValue = ctrl.$viewValue;
         console.log(currentValue);
         //... manipulate the value and update
         ctrl.$setViewValue(currentValue + "Updated");
       };
     },
     replace: true,

   };
 });

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" ng-init="some={obj:{myA:'hey'}}">
  {{some.obj.myA}}
  <x ng-model="some.obj.myA"></x>
</div>

Using $parse

Employ $parse service to generate getter and setter from the expression for updating it back. This method supports multiple attribute bindings.

Example:

   link: function($scope, $element, $attrs) {
       var getA = $parse($attrs.a);
       var setA = getter.assign; 
       var currentValue = getter($scope);
       //... update to new value and set it back
       setA ($scope, currentValue  + "Updated")
     },

angular.module('app', []).directive('x',['$parse', function($parse) {
   var a = {};
   return {
     restrict: 'E',
     link: function($scope, $element, $attrs) {
       var getter = $parse($attrs.a);
       var setter = getter.assign;
       console.log(getter($scope),setter($scope, "Updated"));
     },
     replace: true,

   };
 }]);

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" ng-init="some={obj:{myA:'hey'}}">
  {{some.obj.myA}}
  <x a="some.obj.myA"></x>
</div>

Answer 2

Various ways to implement:

Utilizing ng-model

For instance:

app.directive('x', function() {
  var a = {};
  return {
    require:'ngModel',
    restrict: 'E',
    link: function($scope, $element, $attrs, ctrl) {
       var currentValue = ctrl.$viewValue;
       //... manipulate the value and update
       ctrl.$setViewValue(newValue);
       ctrl.$render();
    },
    replace: true,
    template: ...
  };
});

<x ng-model="some.obj.myA"></x>

If your directive intends to modify the modal's value, consider exploring $formatters/$parsers. Also, refer to $viewChangeListeners for observing view value changes.

 angular.module('app', []).directive('x', function() {
   var a = {};
   return {
     require: 'ngModel',
     restrict: 'E',
     link: function($scope, $element, $attrs, ctrl) {
       //override render function
       ctrl.$render = function() {
         var currentValue = ctrl.$viewValue;
         console.log(currentValue);
         //... manipulate the value and update
         ctrl.$setViewValue(currentValue + "Updated");
       };
     },
     replace: true,

   };
 });

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" ng-init="some={obj:{myA:'hey'}}">
  {{some.obj.myA}}
  <x ng-model="some.obj.myA"></x>
</div>

Using $parse

Employ $parse service to generate getter and setter from the expression for updating it back. This method supports multiple attribute bindings.

Example:

   link: function($scope, $element, $attrs) {
       var getA = $parse($attrs.a);
       var setA = getter.assign; 
       var currentValue = getter($scope);
       //... update to new value and set it back
       setA ($scope, currentValue  + "Updated")
     },

angular.module('app', []).directive('x',['$parse', function($parse) {
   var a = {};
   return {
     restrict: 'E',
     link: function($scope, $element, $attrs) {
       var getter = $parse($attrs.a);
       var setter = getter.assign;
       console.log(getter($scope),setter($scope, "Updated"));
     },
     replace: true,

   };
 }]);

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.23/angular.min.js"></script>
<div ng-app="app" ng-init="some={obj:{myA:'hey'}}">
  {{some.obj.myA}}
  <x a="some.obj.myA"></x>
</div>

Updating parent scope data from within a directive without relying on isolated scope bindings

Answer №1

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