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

Question

I\'m attempting to use an ajax source with Datatables, and I\'ve run into some errors in doing. Previously Ajax was not being used with Datatables, and they were working fin

Answer 1

Your JSON output is wrong for the following reasons:

1. The iTotalRecords and iTotalDisplayRecords fields are missing. This is why the pagination (and all the other functionalities) are broken (notice the message "Showing 1 to NaN of NaN entries (filtered from NaN total entries)" in the footer section). See this page for further details on server-side processing.
2. There is some HTML code after the JSON response.

Here is the extra HTML code (taken from test.php):

<!-- Hosting24 Analytics Code -->
<script src="http://stats.hosting24.com/count.php"></script>
<!-- End Of Analytics Code -->

In my opinion, the test.php script should be like the following:

<?php 

$link = mysqli_init();

// Adjust hostname, username, password and database name before use!
$db = mysqli_real_connect($link, "hostname", "username", "password", "database") or die(mysqli_connect_error());

$SQL = 'SELECT `id`,`Minecraft_Username`,`Block_Name`,`Quantity`,`Cost`,`Trade_Status` FROM mctrade_trades';
$result = mysqli_query($link, $SQL) or die(mysqli_error($link));

$aaData = array();
while ($row = mysqli_fetch_assoc($result)) {
    $aaData[] = $row;
}

$response = array(
  'aaData' => $aaData,
  'iTotalRecords' => count($aaData),
  'iTotalDisplayRecords' => count($aaData)
);
if (isset($_REQUEST['sEcho'])) {
  $response['sEcho'] = $_REQUEST['sEcho'];
}

header('Content-type: application/json'); 
echo json_encode($response);

?>

Be also aware that the mysql_* functions are deprecated, so you should use PDO or MySQLi instead; have a look at this answer for further details.