Adjust the user interface in response to a modification in a directive attribute within AngularJs

Question

Adjust the user interface in response to a modification in a directive attribute within AngularJs

I am currently facing challenges with data binding in AngularJs.

Within my .html file, I have the following markup that includes a custom directive:

<my-directive ng-repeat="i in object" attr-1="{{i.some_variable}}"></my-directive>

Important Note: The 'some-variable' value is updated every 10 seconds (based on the associated collection and passed to the template through the controller).

The code for the directive is as follows:

myApp.directive('myDirective', function () {

  scope: {
   'attr-1': '=attr1'

This results in an exception due to the brackets in attr-1 as shown in the html code above.

However, it functions correctly when using read-only access (noted with the at-sign below):

myApp.directive('myDirective', function () {

  scope: {
   'attr-1': '@attr1'

I utilize scope.attr-1 in the directive's HTML to display its value.

The issue lies in the fact that with read-only access, the UI fails to reflect any changes made to the attribute.

I came across a potential solution involving $parse or $eval, but I struggled to implement them. Are there better alternatives available?

javascript angularjs templates data-binding angularjs-scope

Answer 1

Answer №1

Only utilizing two-way binding is necessary, without the need for $parse or $eval.

Take a look at the demonstration below or in this interactive demo.

This example utilizes $interval to mimic updates, but data can also be updated from various sources like web sockets or ajax requests.

I'm employing the controllerAs and bindToController syntax (requires AngularJS version 1.4 or newer), although using an isolated scope is also possible. Refer to the Angular documentation for more details.

The $watch function in the directive's controller is simply demonstrating how the directive can detect changes in the data.

angular.module('demoApp', [])
.controller('MainController', MainController)
.directive('myDirective', myDirective);

function MainController($interval) {
var self = this,
        refreshTime = 1000; //interval time in ms
    
    activate();
    
    function activate() {
    this.data = 0;
    $interval(updateView, refreshTime);
    }
    
    function updateView() {
    self.data = Math.round(Math.random()*100, 0);
    }
}

function myDirective() {
return {
    restrict: 'E',
        scope: {
        },
        bindToController: {
            data: '='
        },
        template: '<div><p>directive data: {{directiveCtrl.data}}</p></div>',
        controller: function($scope) {
            $scope.$watch('directiveCtrl.data', function(newValue) {
            console.log('data changed', newValue);
            });
        },
        controllerAs: 'directiveCtrl'
    }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.7/angular.js"></script>
<div ng-app="demoApp" ng-controller="MainController as ctrl">
    model value in ctrl. {{ctrl.data}}
    <my-directive data="ctrl.data"></my-directive>
</div>

Answer 2

Only utilizing two-way binding is necessary, without the need for $parse or $eval.

Take a look at the demonstration below or in this interactive demo.

This example utilizes $interval to mimic updates, but data can also be updated from various sources like web sockets or ajax requests.

I'm employing the controllerAs and bindToController syntax (requires AngularJS version 1.4 or newer), although using an isolated scope is also possible. Refer to the Angular documentation for more details.

The $watch function in the directive's controller is simply demonstrating how the directive can detect changes in the data.

angular.module('demoApp', [])
.controller('MainController', MainController)
.directive('myDirective', myDirective);

function MainController($interval) {
var self = this,
        refreshTime = 1000; //interval time in ms
    
    activate();
    
    function activate() {
    this.data = 0;
    $interval(updateView, refreshTime);
    }
    
    function updateView() {
    self.data = Math.round(Math.random()*100, 0);
    }
}

function myDirective() {
return {
    restrict: 'E',
        scope: {
        },
        bindToController: {
            data: '='
        },
        template: '<div><p>directive data: {{directiveCtrl.data}}</p></div>',
        controller: function($scope) {
            $scope.$watch('directiveCtrl.data', function(newValue) {
            console.log('data changed', newValue);
            });
        },
        controllerAs: 'directiveCtrl'
    }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/angular.js/1.4.7/angular.js"></script>
<div ng-app="demoApp" ng-controller="MainController as ctrl">
    model value in ctrl. {{ctrl.data}}
    <my-directive data="ctrl.data"></my-directive>
</div>

Answer 3

Answer №2

Here is the approach I implemented (in case someone encounters a similar issue):

// Custom Directive Implementation

myApp.directive('customDirective', function () { return {
    restrict: 'E',

    templateUrl: function () {
        return 'custom-directive.html';
    },
    scope: {
        'id': '@attrId',
        'x': '@attrX',
        'y': '@attY',
        //....
    },
    link: function ($scope, element, attrs) {

         // *** CUSTOM SOLUTION ***
         attrs.$observe('attrId', function (id) {
             $scope.id = id;
         });
         //...
    }

Update: I received an answer from someone facing a similar challenge, and they devised a solution that closely resembles mine:

Dealing with directive inside ng-repeat and magic of scope '@'

This reference provides insightful explanations behind the concept.

Answer 4

Here is the approach I implemented (in case someone encounters a similar issue):

// Custom Directive Implementation

myApp.directive('customDirective', function () { return {
    restrict: 'E',

    templateUrl: function () {
        return 'custom-directive.html';
    },
    scope: {
        'id': '@attrId',
        'x': '@attrX',
        'y': '@attY',
        //....
    },
    link: function ($scope, element, attrs) {

         // *** CUSTOM SOLUTION ***
         attrs.$observe('attrId', function (id) {
             $scope.id = id;
         });
         //...
    }

Update: I received an answer from someone facing a similar challenge, and they devised a solution that closely resembles mine:

Dealing with directive inside ng-repeat and magic of scope '@'

This reference provides insightful explanations behind the concept.

Adjust the user interface in response to a modification in a directive attribute within AngularJs

Answer №1

Answer №2

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