How can I add other data from a row to a tooltip?

I feel totally new to this, but I have been working on it for days with no luck.

Here are my column definitions I am using. I want to have documentName as the text, and the Document image as the tooltip. But I can only get the data field of that columnto render in the tooltip code. Not the data from another column..

I can render the imagetest in a tooltip in the imagetest column at the end

       {
            data: "contactDocument.documentName",
            "visible": false,
        },
        {
            data: "contactDocument.imagetest2",
            "visible": false,
        },
        {

            data: "contactDocument.documentName",
            render: function (data, type, row) {
                var code = '<object style=" width:300px; height: auto" data="' + row.imagetest2 + '"></object><p class="#dbtooltip" data-toggle="tooltip" title=' + data + '>' + data + '</p>';
                return code;
            }

          data: "contactDocument.imagetest2",
            render: function (imagetest2) {

                var master = '<span class="mytooltip tooltip-effect-1"> <span class="tooltip-item"> <object style="background:white;  width:50px; height: 50px" data="' + imagetest2 + '"></object></span> <span class="tooltip-content clearfix"> <object style=" width:300px; height: auto" data="' + imagetest2 + '"></object></span> </span>'
               var code = master;

                return code;

            }