jquery - Unable to save Ordering to database - Codeigniter -

i using codeigniter , within trying save ordering of list first drag , drop re-order , click save save reordering. however, list not saved. appreciated.

view file:

<div class="container">     <div class="row">         <div class="col-md-8 col-md-offset-2">             <section>                 <h2>order songs</h2>                 <p class="alert alert-info">drag order songs , click 'save'</p>                 <div id="orderresult"></div>                 <? echo form_button('save', 'save', 'class="btn btn-default" id="save" value="save"')?>             </section>         </div>     </div> </div>    <script> $(function() {         $.post('<?php echo site_url('admin/songs/order_ajax'); ?>', {}, function(data){                 $('#orderresult').html(data);         });          $('#save').click(function(){                  osortable = $('.sortable').nestedsortable('toarray');                  $('#orderresult').slideup(function(){                         $.post('<?php echo site_url('admin/songs/order_ajax'); ?>', { sortable: osortable }, function(data){                                 $('#orderresult').html(data);                                 $('#orderresult').slidedown();                         });                 });          }); }); </script> 

order_ajax file:

<?php echo get_ol($songs);  function get_ol ($array, $child = false) {         $str = '';          if (count($array)) {                 $str .= $child == false ? '<ol class="sortable">' : '<ol>';                  foreach ($array $item) {                         $str .= '<li id="list_' . $item['id'] .'">';                         $str .= '<div>' . $item['songname'] .'</div>';                          // have children?                         if (isset($item['children']) && count($item['children'])) {                                 $str .= get_ol($item['children'], true);                         }                          $str .= '</li>' . php_eol;                 }                  $str .= '</ol>' . php_eol;         }          return $str; } ?>  <script> $(document).ready(function(){      $('.sortable').nestedsortable({         handle: 'div',         items: 'li',         toleranceelement: '> div',         maxlevels: 2     });  }); </script> 

the controller:

public function order() {     $data['sortable'] = true;     $data['title'] = 're-order';     $data['module'] = 'admin';     $data['header_file'] = 'admin_header';     $data['nav_file'] = 'admin_nav';     $data['view_file'] = 'song_order';     $data['script_file'] = 'admin_script';     echo modules::run('template/template_admin', $data); }  public function order_ajax() {     // save order ajax call     if (isset($_post['sortable'])) {         $this->mdl_admin_songs->save_order($_post['sortable']);     }      // fetch pages     $data['songs'] = $this->mdl_admin_songs->get_nested();      // load view     $this->load->view('song_order_ajax', $data); } 

the model:

public function get_nested() {     $songs = $this->db->get('songrequest')->result_array();      $array  = array();     foreach ($songs $song) {         if (!$song['parent_id']) {             $array[$song['id']] = $song;         }         else {             $array[$song['parent_id']]['children'][] = $song;         }     }     return $array; }  public function save_order($songs) {     if (count($songs)) {         foreach ($songs $order => $song) {             if ($song['item_id'] != '') {                 $data = array('parent_id' => (int) $song['parent_id'], 'order' => $order);                 $this->db->set($data)->where($this->_primary_key, $song['item_id'])->update($this->_table_name);             }         }     } } 

thanks, naveen