Data object not displaying data in my table

Genesis

Hi Peeps

Completely noooob at this but if anyone can assist me i would highly appreciate it. I have tried various threads to and nothing is working. Please HELP... If you have any suggestions of how ever else i can do it, please state so, working on a REST API thats needs authentication sent as well.
Example of my json object (Its rather a huge source so im cutting it short just to give you an idea of what im working with):

{
objects: [
{
id: "2717eb66-95d3-11e6-860e-001e67260782",
type: "alert",
updated_at: "2016-10-19T08:08:21Z",
display: "You Win",
sighting_id: "26341|1476864434252|1",
source_system_id: "CLE",
alert_id: "27d0992dfba243cab09ebfa18503b89e",
timestamp: "2016-10-19T08:07:16Z",
time_string: "10:07",
alert_type_id: {
key: 2,
display: "Winner"
}.........

here is my Javascript:

var xhr = new XMLHttpRequest();
        xhr.open("GET", api_url, true);
        xhr.withCredentials = true;
        xhr.setRequestHeader("Authorization", 'Basic  '+btoa(username+':'+password));
        xhr.onload = function() {
            var obj = jQuery.parseJSON(xhr.responseText);
            $('#maintable').dataTable({
                "processing": true,
                "aaData": obj,
                "aoColumns": [
                        { "mData": "objects.id" },
                        { "mData": "objects.type" },
                        { "mData": "objects.updated_at" },
                        { "mData": "objects.display"},
                        { "mData": "objects.timestamp"}
                        ]
            });
        };
        xhr.send();

My Html:

<div class="container">
    <table id="maintable" class="table table-striped table-condensed">
        <thead>
        <tr>
            <th>id</th>
            <th>type</th>
            <th>updated_at</th>
            <th>display</th>
            <th>timestamp</th>
        </tr>
        </thead>
        <tfoot>
        <tr>
            <th>id</th>
            <th>type</th>
            <th>updated_at</th>
            <th>display</th>
            <th>timestamp</th>
        </tr>
        </tfoot>
        <tbody>

        </tbody>
    </table>
</div>