Angular Directives: Link to Controller without Services

Question

I'm gradually getting the hang of Angular directives and so far, have resorted to creating a service as an intermediary between controllers.

I was just wondering, in the context of directives (and linking functions) is it possible to give the controller access to variables from the linking function? (Without a service or global variables).

module.exports = function() {
    return {
      restrict: 'A',
      templateUrl: 'partials/collection',
      link: function(scope, element, attrs) {
        var name = attrs.collectionName;
        // from here
      },
      controller: function($scope, socket) {
        $scope.models = [];
        // to here
        socket.on('ready', function() {
          socket.emit(name + '/get');
        });

      }
    }  
  };

I want the collection-name attribute's value to be available within my controller, so that I can make appropriate socket calls. Any idea?

Answer 1

They share the same scope, so this should work.

module.exports = function() {
    return {
      restrict: 'A',
      templateUrl: 'partials/collection',
      link: function(scope, element, attrs) {
        scope.name = attrs.collectionName;
        // from here
      },
      controller: function($scope, socket) {
        $scope.models = [];
        // to here
        socket.on('ready', function() {
          socket.emit($scope.name + '/get');
        });

      }
    }  
  };

Answer 2

You can add a method on the controller and the call it from the link function.

controller: function($scope, socket) {
   this.setSocket = function(name){
       {...}
   }
}

On link:

link: function(scope, element, attrs, controller){
    var name = attrs.collectionName; 
    controller.setSocket(name);
}

Answer 3

There are a couple of ways of doing what you want

• Just put everything in the link function. You can set functions and variables on the scope just like you might put in a controller.

• Just put everything in the controller, in terms of setting scope variables or functions. It is injected with $attrs, which contains the normalised attribute values, so you have access to the attributes if you need them.

As far as I know, in most cases it doesn't make a difference where you assign variables or functions on the scope. The main difference between the two is that if you want to give your directive a public API, so other directives can communicate to it via require, then you must use this.something in the controller.

Answer 4

There maybe a better way to do it, but I've managed to get around the problem by changing my controller functions dependencies to include an $element argument. Then just used jqLite to get the value of the attribute in question.

controller: function($scope, $element, socket) {
   var name = $element.attr('collection-name');
}

It's not fantastically elegant, but it works.