DataTables with Dynamic Columns

Question

I'm trying to render a datatable with dynamic columns using JSON but keep getting the following error:

Uncaught TypeError: Cannot read property 'length' of undefined.

Any help would be greatly appreciated.

Thanks!!

JS:

<link href="http://cdn.datatables.net/1.10.4/css/jquery.dataTables.css" rel="stylesheet" type="text/css"/>

<script src="http://cdn.datatables.net/1.10.4/js/jquery.dataTables.js" type="text/javascript"></script>

jQuery(document).ready(function() {
    var dataObject = '[{"COLUMNS":[{ "sTitle": "NAME"}, { "sTitle": "COUNTY"}],"DATA":[["John Doe","Fresno"],["Billy","Fresno"],["Tom","Kern"],["King Smith","Kings"]]}]';

    var columns = [];

    jQuery.each(dataObject.COLUMNS, function(i, value){
        var obj = { sTitle: value };
        columns.push(obj);
    });

    jQuery('#example').dataTable({
        "bProcessing": true,
        "bPaginate": true,
        "sPaginationType": "full_numbers",
        "aaData": dataObject.DATA,
        "aoColumns": columns
    });
});

HTML:

<table cellpadding="0" cellspacing="0" border="0" class="display" id="example">
    <tr><thead>column1</thead></tr>
    <tbody></tbody>
</table>

Answer 1

Hi there are several issue in the code...

• dataObject is string, not a json. so you can make it json object using eval() or removing '
• the parameter name you are passing in datatable is wrong. you need to provide the accurate parameter.
• You are using the parent json object as array. but you are not using [] to get its first element.
• your html content is the table is wrong. since you are passing the columns name using java script. you dont need the html table headers. the length error actually occurring because of this html code. if you remove the html inside the tables then your code will not have the length error. but still the above error i mentioned will be there. please check the code bellow. may be you are looking for this code...

jQuery(document).ready(function() {
    var dataObject = eval('[{"COLUMNS":[{ "title": "NAME"}, { "title": "COUNTY"}],"DATA":[["John Doe","Fresno"],["Billy","Fresno"],["Tom","Kern"],["King Smith","Kings"]]}]');
    var columns = [];
    $('#example').dataTable({
        "data": dataObject[0].DATA,
        "columns": dataObject[0].COLUMNS
    });
});

<table cellpadding="0" cellspacing="0" border="0" class="display" id="example">
</table>

Answer 2

I think life would have been easier with with this

jQuery(document).ready(function() {
  var dataObject = {
    columns: [{
      title: "NAME"
    }, {
      title: "COUNTY"
    }],
    data: [
      ["John Doe", "Fresno"],
      ["Billy", "Fresno"],
      ["Tom", "Kern"],
      ["King Smith", "Kings"]
    ]
  };
  var columns = [];
  $('#example').dataTable({
    "data": dataObject.data,
    "columns": dataObject.columns
  });
});

<link href="https://cdn.datatables.net/1.10.9/css/jquery.dataTables.min.css" rel="stylesheet" />
<script src="https://code.jquery.com/jquery-2.1.4.min.js"></script>
<script src="https://cdn.datatables.net/1.10.9/js/jquery.dataTables.min.js"></script>
<table cellpadding="0" cellspacing="0" border="0" class="display" id="example">

Answer 3

Those who get a Warning: Requested unknown error described on https://datatables.net/tn/4, do check your json data format. Below example may help you.

var dataObject = eval('[{"columns":[{ "title": "Id", "data":"Id"}, { "title": "Name", "data":"Name"}],"data":[{"Id":"123","Name":"John Doe Fresno"}, {"Id":"124","Name":"Alice Alicia"}]}]');    
$('#example').DataTable(dataObject[0]);

working demo: https://jsfiddle.net/ue6vqy77/