[Solved]-HighChart dynamic drill down-Highcharts

$(function () {    

// Create the chart
$('#container').highcharts({
    chart: {
        type: 'column',
        events: {
            drilldown: function (e) {
                if (!e.seriesOptions) {

                    var chart = this,
                        drilldowns = {
                            'Animals': {
                                name: 'Animals',
                                data: [
                                    ['Cows', 2],
                                    ['Sheep', 3]
                                ]
                            },

                            'Fruits': {
                                name: 'Fruits',
                                data: [
                                    ['Apples', 5],
                                    ['Oranges', 7],
                                    ['Bananas', 2]
                                ]
                            },
                            'Cars': {
                                name: 'Cars',
                                data: [
                                    {
                                    name: 'Toyota',
                                    y: 4,
                                    drilldown: true
                                    },
                                    ['Volkswagen', 2],
                                    ['Opel', 5]
                                ]
                            }

                        },


                        series = drilldowns[e.point.name];

                    // Show the loading label
                    chart.showLoading('Simulating Ajax ...');

                    setTimeout(function () {
                        chart.hideLoading();
                        chart.addSeriesAsDrilldown(e.point, series);
                    }, 1000);
                }

            }
        }
    },
    title: {
        text: 'Async drilldown'
    },
    xAxis: {
        type: 'category'
    },

    legend: {
        enabled: false
    },

    plotOptions: {
        series: {
            borderWidth: 0,
            dataLabels: {
                enabled: true,
            }
        }
    },

    series: [{
        name: 'Things',
        colorByPoint: true,
        data: [{
            name: 'Animals',
            y: 5,
            drilldown: true
        }, {
            name: 'Fruits',
            y: 2,
            drilldown: true
        }, {
            name: 'Cars',
            y: 4,
            drilldown: true
        }]
    }],

    drilldown: {
        series: []
    }
})

});

I found the solution to this. Actually when data is fetched from web service as json for the next level of drilldown I had to make sure the property drilldown needed to be set to true which I was not doing earlier after some research I found it. I have given some data in json format below with reference to the example on fiddle.

When first level was clicked I was going to web service and fetching data as

  "{\"name\":\"Animals\",\"data\": [[\"Cows\", 2],[\"Sheep\", 3]],\"drilldown\": true}"

which was not enabling drilldown for the next level. In order to allow drill down further I had to modify the above data as below where in I have added property drilldown to be as true

  (name == "Animals") resp = "{\"name\":\"Animals\",\"data\": [{\"name\":\"Cows\", \"y\": 2, \"drilldown\": \"true\"},{\"name\":\"Sheep\",\"y\": 3,\"drilldown\":\"true\"}]}";

That is all, seems simple :) Will try to create sample on Fiddle if I get time and will update link if done so.