Cant read properties of Object in meteor 's iron router's route

I want to pass object in data context in route. I am trying to read JavaScript object(which holds the business logic) . If i send the object as such , then i can read it's properties in template. But if i try to send a custom object by reading some of it's properties . Then I am getting error that it can not read properties of same object.

this.route('updateBook/' ,
        {
        path:'/updateBook',
    loadingTemplate: 'loading',
    data : function(){
                var Book = Books.findOne({hasFinished:true});

  var UpdateBookObject ={};
    //UpdateBookObject.currentPage = Book.currentPage;
    UpdateBookObject.name = Book.name;  
    UpdateBookObject.author = Book.author;
    // UpdateBookObject.img = Book.img;
    UpdateBookObject.numOfPages = Book.numOfPages;
    UpdateBookObject.dateStarted = Book.dateStarted;
    UpdateBookObject.dateToFinish = Book.dateToFinish;
    UpdateBookObject.percentage = (UpdateBookObject.currentPage/UpdateBookObject.numOfPages).toFixed(2);
    UpdateBookObject.pagesRemaining = UpdateBookObject.numOfPages - UpdateBookObject.currentPage;
    var finishMoment = moment(UpdateBookObject.dateToFinish,"DD-MM-YYYY");
    var startMoment = moment(UpdateBookObject.dateStarted,"DD-MM-YYYY");
  UpdateBookObject.perDayToRead = finishMoment.diff(startMoment,'days');
  return UpdateBookObject;                      
            }


        });