datatable columns

stang1013

I'm trying to render the column with handlebars helper:
columns:[
{data: "timestamp", defaultContent: "",
render: function(data, type, row) {
//return ${data};
return "{{format_date data}}";
}
},
...]
In handlebar:
registerHelper('format_date', function(date){
if (date) {
return dateFormat(date, "yyyy-mm-dd HH:MM:ss");
} else {
return "";
}
});
I found the data never get passed to handlebars helper? anyone could shed a light?

Thanks.