ngResourc：生成唯一编号

Question

我正在尝试发布新数据评论，我希望$ resource serviceto自动给每个评论唯一ID。但我不知道该怎么做。数据已经过去，但是id属性为空，它没有id号。

controller.js的代码

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: 
    For input string: ""

service.js

    .controller('ContactController', ['$scope','FeedbackFactory', function($scope,FeedbackFactory) {

        $scope.feedback = {mychannel:"", firstName:"", lastName:"", agree:false, email:"" ,id:""};

        var channels = [{value:"tel", label:"Tel."}, {value:"Email",label:"Email"}];

        $scope.channels = channels;
        $scope.invalidChannelSelection = false;

                     $scope.fback= FeedbackFactory.putFeedback().query(

                        function(response){
                            $scope.fback = response;

                        },
                        function(response) {
                            $scope.message = "Error: "+response.status + " " + response.statusText;
                        }
        );

    }])




    .controller('FeedbackController', ['$scope', 'FeedbackFactory',function($scope,FeedbackFactory) {

        $scope.sendFeedback = function() {

            console.log($scope.feedback);

            if ($scope.feedback.agree && ($scope.feedback.mychannel === "")) {
                $scope.invalidChannelSelection = true;
                console.log('incorrect');
            }
            else {
                    $scope.invalidChannelSelection = false;
                  $scope.fback.push($scope.feedback);
          FeedbackFactory.putFeedback().save($scope.fback);

                $scope.feedback = {mychannel:"", firstName:"", lastName:"", agree:false, email:"" };
                $scope.feedback.mychannel="";
                $scope.feedbackForm.$setPristine();
                console.log($scope.feedback);
            }
        };
    }])

注意：数据注释将以JSON数据的形式保存。