unable to access rootscope var in directive scope

Question

The function below defines a variable in the rootscope.

function MyCtrl($scope, $rootScope) {
  $rootScope.buttons = [{href: '#/students', icon:'icon-ok'},
                         {href: '#/students', icon:'icon-remove'},
                         {href: '#/students/new', icon:'icon-plus'}];
}
MyCtrl.$inject = ['$scope', '$rootScope'];

The html in the directive below depends upon a variable in the rootscope -

angular.module('btnbar.directive', []).
directive("btnBar", function(){
  return {
    restrict: 'E',
    scope :{},
    controller: function($scope, $element,$rootScope) {
    },
    template:'<div class="btn-toolbar">' +
      '<a class="btn" ng-repeat="b in buttons" href={{b.href}}>' +
      '<i class={{b.icon}}></i></a></div>',
    replace:true
  }
});

However the above code doesnt work. It works if I directly define the 'buttons' var in the directive scope.

Answer 1

You have an isolate scope in your directive

scope:{}

This means that the directive doesn't have access to upper scopes - remember that isolate scopes don't prototypically inherit from the parent scope. So you either remove the isolate scope or tell the directive to bind some properties to its local scope from the parent scope.

scope: {buttons: '='}

Then invoke the directive like this

<btn-bar buttons="buttons"></btn-bar>

Example: http://plnkr.co/edit/88R66L7uAHoezDZvuoH5?p=preview

---

Also, rather than modifying the $rootScope from a controller, you might want to do it from the run method

var app = angular.module('app', ['btnbar.directive']);

app.run(function($rootScope){
  $rootScope.buttons = [{href: '#/students', icon:'icon-ok'},
                        {href: '#/students', icon:'icon-remove'},
                        {href: '#/students/new', icon:'icon-plus'}];
});

Answer 2

Try:

<a class="btn" ng-repeat="b in $root.buttons" href={{b.href}}>