Retrieve the $scope object within an isolated directive

Is there a way to modify a $scope variable from within an isolated directive?

I've experimented with the '@, =, &' syntax in the directive scope but haven't been successful.

Here's a simplified version of my code:

JS

app.controller('testCtrl', function($scope) {
    $scope.hello = 'hello';
}

app.directive('testDirective', function() {
    return {
        restrict: 'E',
        template: '<div>{{text}}</div>',
        scope: {},
        link: function(scope, element) {
            scope.text = 'this is my text';
            scope.hello = 'hello world!';
        }
    };
});

HTML

<body>
    {{ hello }}
    <test-directive />
</body>

This is the desired output:

hello world!
this is my text

Answer №1

If you want to specify a parent controller in your directive, you can use the require option. This will allow you to access the controller in your link function as the last argument:

app.directive('testDirective', function() {
    return {
        restrict: 'E',
        template: '<div>{{text}}</div>',
        require: '^testCtrl',
        scope: {},
        link: function(scope, element, attrs, testCtrl) {
            scope.text = 'this is my text';
            testCtrl.setHello('hello world!');
        }
    };
});

Just remember that you need to define the setHello() method on your controller to make this work. You are getting the controller object itself, not its injected scope:

app.controller('testCtrl', function($scope) {
    $scope.hello = 'hello';
    this.setHello = function(newHello) {
      $scope.hello = newHello;
    }
}

If you're more flexible and don't necessarily need to strictly enforce the controller dependency, you can directly access scope.$parent.$parent.hello from within your directive.

Answer №2

To follow HTML conventions, directives should be written in snake-case:

<sample-directive />

When defining directives in your script, use camel case like this:

app.directive('sampleDirective', function() {
});

Don't forget to include the ngController directive as well:

<body ng-controller="sampleCtrl">
</body>

Answer №3

Here are some key points that were missing in the explanation:

  1. The ng-controller was not properly defined.
  2. Understanding that @ means passing an attribute as a string, = means binding the property to a parent's scope (which is necessary here), and & means passing in a function from the parent's scope to be called later.
  3. When naming the directive "testDirective", it should be written in HTML as
    <test-directive></test-directive>
    , as camel case words in JS need to be separated by "-" in HTML.

<body ng-controller="testCtrl">
    {{ hello }}
    <test-directive hello-from-parent="hello"></test-directive>
</body>

app.directive('testDirective', function() {
  return {
      restrict: 'E',
      scope: {
        hello: "=helloFromParent"
      },
      template: '<div>{{text}}</div>',
      link: function(scope, element, attrs) {
        scope.text = 'this is my text';
        scope.hello = 'hello world';
      }
  }
});

A functional example can be found in this working plunker

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