Access Parent Scope in Transcluded Directive

Question

I would like to access a parent directive's scope, but I can't seem to get the right combination of settings. Is this possible and is it the right approach?

I really want to avoid putting something like SOME_CONST (which would help me make DOM updates through control flow) in MyCtrl

<div ng-controller="MyCtrl">
    <parent>
        <child></child>
    </parent>
</div>

var myApp = angular.module('myApp',[]);

function MyCtrl($scope) {
    $scope.obj = {prop:'foo'};
}

myApp.directive('parent', function() {
    return {
        scope: true,
        transclude: true,
        restrict: 'EA',
        template: '<div ng-transclude><h1>I\'m parent {{obj.prop}}<h1></div>',
        link: function(scope, elem, attrs) {
            scope.SOME_CONST = 'someConst';
        }
    }
});

myApp.directive('child', function() {
    return {
        restrict: 'EA',
        template: '<h1>I\'m child.... I want to access my parent\'s stuff, but I can\'t.  I can access MyCtrlScope though, see <b>{{obj.prop}}</b></h1> how can I access the <b>SOME_CONST</b> value in my parent\'s link function?  is this even a good idea? {{SOME_CONST}}.  I really don\'t want to put everything inside the MyCtrl',
    }
});

Please see this fiddle

Thanks

Solution 1

With transclude: true and scope: true, the parent directive creates two new scopes:

Scope 004 is a result of scope: true, and scope 005 is a result of transclude: true. Since the child directive does not create a new scope, it uses transcluded scope 005. As you can see from the diagram there is no path from scope 005 to scope 004 (except via private property $$prevSibling, which goes in the opposite direction of $$nextSibling -- but don't use those.)

@joakimbl's solution is probably best here, although I think it is more common to define an API on the parent directive's controller, rather than defining properties on this:

controller: function($scope) {
    $scope.SOME_CONST = 'someConst';
    this.getConst = function() {
       return $scope.SOME_CONST;
    }
}

Then in the child directive:

link:function(scope,element,attrs,parentCtrl){
    scope.SOME_CONST = parentCtrl.getConst();
},

This is how the tabs and pane directives work on Angular's home page ("Create Components" example).

Solution 2

Normally the way you access a parent scope variable in a directive is through bi-directional binding (scope:{model:'=model'} - see the angular guide on directives) in the directive configuration), but since you're using transclusion this is not so straight forward. If the child directive will always be a child of the parent directive you can however configure it to require the parent, and then get access to the parent controller in the child link function:

myApp.directive('parent', function() {
  return {
    scope: true,
    transclude: true,
    restrict: 'EA',
    template: '<div ng-transclude><h1>I\'m parent {{obj.prop}}<h1></div>',
    controller: function($scope) {
        $scope.SOME_CONST = 'someConst';
        this.SOME_CONST = $scope.SOME_CONST;
    }
  }
});

myApp.directive('child', function() {
  return {
    restrict: 'EA',
    require:'^parent',
    scope:true,
    link:function(scope,element,attrs,parentCtrl){
        scope.SOME_CONST = parentCtrl.SOME_CONST;
    },
    template: '<h1>I\'m child.... I want to access my parent\'s stuff, but I can\'t.  I can access MyCtrlScope though, see <b>{{obj.prop}}</b></h1> how can I access the <b>SOME_CONST</b> value in my parent\'s link function?  is this even a good idea? {{SOME_CONST}}.  I really don\'t want to put everything inside the MyCtrl',
  }
});

See this update: http://jsfiddle.net/uN2uv/

Solution 3

I just had the same problem and finally solved it with the angular manual ;)

In short: you need to use a controller in your parent directive and require that controller in your child directive. This way you are able to get your parent properties.

See https://docs.angularjs.org/guide/directive Chapter: Creating Directives that Communicate

I changed your fiddle to use a controller, now you can access your constant: https://jsfiddle.net/bbrqdmt3/1/

var myApp = angular.module('myApp',[]);

function MyCtrl($scope) {
    $scope.obj = {prop:'foo'};
}

myApp.directive('parent', function() {
    return {
        scope: true,
        transclude: true,
        restrict: 'EA',
        template: '<div ng-transclude><h1>I\'m parent {{obj.prop}}<h1></div>',
        controller: function($scope) {
            this.getConst= function() {
                return 'someConst';
            }                        
        },
    }
});

myApp.directive('child', function() {
    return {
        restrict: 'EA',
        require : '^parent',
        link: function(scope, element, attrs, ctrl) {
            scope.value= ctrl.getConst();
        },
        template: '<h1>I\'m child.... I want to access my parent\'s stuff, but I can\'t.  I can access MyCtrlScope though, see <b>{{obj.prop}}</b></h1> how can I access the <b>SOME_CONST</b> value in my parent\'s link function?  is this even a good idea? {{value}}.  I really don\'t want to put everything inside the MyCtrl',
    }
});