Reading local XML file doesn't work on device

Good morning,

i have written a XML file and put it into the /www/res/ folder of my ionic project. The app reads the file with $http.get.

Within the browser, this code works fine, but on the android device it seems that the file can't be read. What am i doing wrong?

Thanks in advance, Lukas

Source:

angular.module('topicData.service', []).factory('DataSource', ['$http',
function($http) {
return {
        get : function(file, callback, transform) {
            $http.get(file, {
                transformResponse : transform
            }).success(function(data, status) {
                console.log("Request succeeded: "+file);
                callback(data);
            }).error(function(data, status) {
                console.log("Request failed " + status);
                alert(data);
            });
        }
    };
}]);

Source file path definition:

    $scope.TOPIC_FILE = "../res/topic_table.xml";