Optional expression attribute in AngularJS directive

Question

I have a custom navigation directive that needs an optional "disable" attribute, and I'm not sure if it's even possible.

In my main controller:

.controller('NavCtrl', ['UserResource','RoleResource'], function(UserResource,RoleResource){
      var user = UserResource.getUser();
      var roles = RoleResource.getRoles();
      UserService.init(user, roles); //????

});

In my directive:

.directive('navItem', function(){
    return{
        restrict: 'A',
        scope: {
            text: '@',
            href: '@',
            id: '@',
            disable: '&'

        },
        controller: function($scope, $element, $attrs){
            $scope.disabled = ''; //Not sure I even need a controller here
        },
        replace: true,
        link: function(scope, element, attrs){
            scope.$eval(attrs.disable);
        },
        template: '<li class="{{disabled}}"><a href="{{href}}" id="{{id}}">{{text}}</a></li>'

    }

});

In my HTML, I want to do something like this:

<div data-nav-item text="My Text" href="/mytemplate.html" id="idx"
     disable="UserService.hasRole('ADMIN,BILLING') && someOtherFn(xxx) || ...">

Solution

You could make what you have work by chaning your $eval call to

scope.$parent.$eval(attrs.disable);

because you need to evaluate the expression contained in attrs.disable in the parent scope, not the directive's isolate scope. However, since you are using the '&' syntax, it will evaluate the expression in the parent scope automatically. So just do the following instead:

if(angular.isDefined(attrs.disable)) {
    scope.disable();
}

Fiddle.

Comments

[Rajkamal Subramanian]

Sorry, i accidentally pressed ctrl+s.. the fiddle got updated with my changes. Could you please update the fiddle link. Sorry once again.

[Mark Rajcok]

@rajkamal, the link above to the fiddle should still take people to the original version, even if you saved a new one. You would have also have had to click the "Base" button to cause people to see your version, so no harm done.

[boyceofreason]

This was exactly what I needed. Thanks!

[Dana Cartwright]

Wow, seeing the scope.disable(); call really helped me. I didn't grasp the full power of '&' until I saw that.