如何在DataTable内部调用getJSON渲染函数？

Question

我刚开始学习dataTables。

是否可以在DataTable渲染函数中使用getJson（）来渲染表数据？

我从console.log（类别）获取未定义;此刻。

我在这里错过了什么吗？

function loadHelpdeskTickets(id) {

$.getJSON(HELPDESKTICKETS_URL + "?filter[where][customerId]=" + id, function(data) {

    var table = $('#helpdesk_table').DataTable({
        data: data,
        "order": [
            [1, "desc"]
        ],
        "processing": true,
        "bLengthChange": true,
        "bFilter": true,
        "bInfo": true,
        "paging": true,
        "columns": [{
                data: "id"
            },
            {
                data: "ticketOpen",
                render: function(data, type, row) {

                    date = new Date(data);
                    return date.toLocaleString("en-GB");
                }
            },
            {
                data: "category",
                render: function(data, type, row) {

                    var category;

                    $.getJSON(HELPDESKQUESTIONS_URL + "?filter[where][id]=" + data, function(data) {
                        $.each(data, function(key, val) {
                            console.log(val.type);
                            category = val.type;
                        });
                    });

                    console.log(category);
                    return category;
                }
            },
            {
                data: "userId"
            },
            {
                data: "installerId"
            }

        ]
    });
});

}