Pass Array from Controller to Factory error

Question

I have a factory thats using angular-websocket to connect with a backend and I need to pass info from my controller to it so that it would send that info and I want to pass it as an array. Factory is as such:

.factory('registerService', function($websocket) {
  var dataStream = $websocket('ws://localhost:3000'); //websocket
  dataStream.onOpen(function() {
    console.log('in');
    this.sendId = function(data) {
    console.log('data: '+data);
    };
  })
  dataStream.send(function(message) {
    //send info to backend
  });
})

And controller as such:

.controller("registerController", function($scope,$stateParams,$ionicPopup,$state,registerService) {
  $scope.registerService = registerService;
  $scope.signUp = function() {
        registerBox = [];
        registerBox.push('Register')
        registerService.sendId(registerBox);
  };
})

However I get error: registerService.sendId is not a function. Whats the problem please?

Answer 1

     .factory('registerService', function($websocket) {
          var dataStream = $websocket('ws://localhost:3000'),
              _this = this;

          dataStream.onOpen(function() {
            console.log('in');
            _this.sendId = function(data) {
               console.log('data: '+data);
            };
          })
          dataStream.send(function(message) {
            //send info to backend
          });

         return _this;
   });