Receive ng-init value from the controller for angular js

I put data in the ng-init then I want to receive these value for my controller.

<div  ng-controller='hotelDetailCtrl' data-ng-init="mytest='hello'" class="col-sm-9 col-lg-9" >



app.controller('hotelDetailCtrl', function ($scope, $http) {
    $scope.init = function(){           
        alert($scope.detailUrl);
    };

});

But I can't get these value from my controller.Please help me and then explain about these case.