librenms/html/pages/alert-log.inc.php

<?php
$param = array();

$pagetitle[] = "Alert Log";
print_optionbar_start();
?>

<form method="post" action="" class="form-inline" role="form" id="result_form">
    <div class="form-group">
      <label>
        <strong>Device</strong>
      </label>
      <select name="device_id" id="device_id" class="form-control input-sm">
        <option value="">All Devices</option>
        <?php
          foreach (get_all_devices() as $hostname)
          {
            echo("<option value='".getidbyname($hostname)."'");
            if (getidbyname($hostname) == $_POST['device_id']) { echo("selected"); }
            echo(">".$hostname."</option>");
          }
        ?>
      </select>
    </div>
    <button type="submit" class="btn btn-default input-sm">Filter</button>
</form>

<?php
print_optionbar_end();
            echo('<div class="panel panel-default panel-condensed">
                <div class="panel-heading">
                    <div class="row">
                        <div class="col-md-2">
                            <strong>Alert Log entries</strong>
                        </div>
                        <div class="col-md-2 col-md-offset-8">
                            <div class="pull-right pdf-export"></div>
                        </div>
                    </div>
                </div>
            ');
?>

<table id="alertlog" class="table table-hover table-condensed table-striped">
    <thead>
        <tr>
            <th data-column-id="humandate" data-order="desc">Time logged</th>
            <th data-column-id="hostname">Device</th>
            <th data-column-id="alert">alert</th>
            <th data-column-id="status" data-sortable="false">Status</th>
        </tr>
    </thead>
</table>
</div>

<script>

var grid = $("#alertlog").bootgrid({
    ajax: true,
    post: function ()
    {
        return {
            id: "alertlog",
            device_id: '<?php echo htmlspecialchars($_POST['device_id']); ?>'
        };
    },
    url: "/ajax_table.php"
}).on("loaded.rs.jquery.bootgrid", function() {

    var results = $("div.infos").text().split(" ");
    low = results[1] -1 ;
    high = results[3];
    max = high - low;
    search = $('.search-field').val();

    $(".pdf-export").html("<a href='pdf.php?report=alert-log&device_id=<?php echo $_POST['device_id'];?>&string="+search+"&results="+max+"&start="+low+"'><img src='images/16/pdf.png' width='16' height='16' alt='Export to pdf'> Export to pdf</a>");
});
</script>