Passing Payload to Chart Data

[digitlimit]

Is there a way to pass extra information or payload to data columns. I wish to pass a payload to data which I will retrieve on mouse event. I don't know how best to implement this.

var chart2 = c3.generate({
    bindto: '#chart2',
    legend: {
        position: 'inset'
    },
    data: {
        columns: [
            ['data1', 30,  payload:{user_id: 1, location: 'Canada'}],
            ['data2', 130, payload:{user_id: 2, location: 'USA'}],
            ['data3', 130, payload:{user_id: 3, location: 'UK'}]
        ],
        type : 'pie',
        onclick: function (d, i, payload) {
            // Here I wish to retrieve the payload
            // use the payload for something
        }
    }
});