try{
  if(typeof order_data == 'undefined')
  {
      var column_name = '_id';
      var column_sort_order = 'desc';
  }
  else
  {
      
      var column_index = req.query.order[0]['column'];
      var column_name = req.query.columns[column_index]['data'];
      var column_sort_order = req.query.order[0]['dir'];
  }
  console.log(column_name);
  console.log(column_sort_order);
  
  const data_arr= await EAVerificationModel.find({'adminid':adminID},{applicantname:1,_id:1}).sort({column_name:column_sort_order}).limit(limit).skip(startIndex).exec();
  console.log(data_arr);
tried different different methods like asc,desc,1,-1 still didnt work, 
can anyone tell me what im doing wrong 

try {
  let sortObj = {};
  if (order_data) {
    const column_index = req.query.order[0]['column'];
    const column_name = req.query.columns[column_index]['data'];
    const column_sort_order = req.query.order[0]['dir'];
    sortObj[column_name] = column_sort_order;
  } else {
    sortObj = { _id: 'desc' };
  }
  const data_arr = await EAVerificationModel.find(
    { adminid: adminID },
    { applicantname: 1, _id: 1 }
  )
    .sort(sortObj)
    .limit(limit)
    .skip(startIndex)
    .exec();
  console.log(data_arr);
} catch (e) {}