How to get updated sortable list in Jquery Sortable widgets

Question

I am trying to provide dynamic ui by adding jquery Sorting methods. The end result is the new sorted list stored in a txt file using PHP. Unfortunately in the newly created file "sort.txt" The new list is not written!
The error seems to be js in update function of sortable div.
var sorted = $( ".column" ).sortable( "serialize", { key: "sort" } );
How to get the sorted ids? Code:

HTML

<div class="column"> 
          <div class="portlet" id="feeds">
            <div class="portlet-header" name="feeds">Feeds</div>
            <div class="portlet-content">Lorem ipsum dolor sit amet, consectetuer adipiscing elit</div>
          </div>

          <div class="portlet" id="news">
            <div class="portlet-header">News</div>
            <div class="portlet-content">Lorem ipsum dolor sit amet, consectetuer adipiscing elit</div>
          </div>

          <div class="portlet" id="shopping">
            <div class="portlet-header" name="shopping">Shopping</div>
            <div class="portlet-content">Lorem ipsum dolor sit amet, consectetuer adipiscing elit</div>
          </div>

          <div class="portlet" id="links">
            <div class="portlet-header">Links</div>
            <div class="portlet-content">Lorem ipsum dolor sit amet, consectetuer adipiscing elit</div>
          </div>

          <div class="portlet" id="images">
            <div class="portlet-header">Images</div>
            <div class="portlet-content">Lorem ipsum dolor sit amet, consectetuer adipiscing elitasdasdasdasdasdasd</div>
          </div>
</div> 

JS:

 $(function() {
    $( ".column" ).sortable({
      connectWith: ".column",
      handle: ".portlet-header",
      cancel: ".portlet-toggle",
      placeholder: "portlet-placeholder ui-corner-all",
      update: function(event, ui) {
        var sorted = $( ".column" ).sortable( "serialize", { key: "sort" } );
            $.post( "sort1.php",{ 'choices[]': sorted});  
        }
    });

    $( ".portlet" )
      .addClass( "ui-widget ui-widget-content ui-helper-clearfix ui-corner-all" )
      .find( ".portlet-header" )
        .addClass( "ui-widget-header ui-corner-all" )
        .prepend( "<span class='ui-icon ui-icon-minusthick portlet-toggle'></span>");

    $( ".portlet-toggle" ).click(function() {
      var icon = $( this );
      icon.toggleClass( "ui-icon-minusthick ui-icon-plusthick" );
      icon.closest( ".portlet" ).find( ".portlet-content" ).toggle();
    }); 
  });

PHP

<?php
    $data = $_POST["choices"];
    $newarray = explode("&", $data[0]);
    $filename = 'sort.txt';
    $handle = fopen($filename, "w");    
    $i = count($newarray);
    foreach ($newarray as $key => $value) {
        fwrite($handle, $value."\n");
    }   
    fclose($handle);    
?>

Answer 1

PHP and JS was bugged.

JS error: var sorted = $( ".column" ).sortable( "serialize", { key: "sort" } );

PHP Error $newarray = explode("&", $data[0]);

Solution:

JS:

 $( ".column" ).sortable({
      axis: 'y',
      connectWith: ".column",
      handle: ".portlet-header",
      cancel: ".portlet-toggle",
      placeholder: "portlet-placeholder ui-corner-all",
      update: function(event, ui) {
        var sorted = $(".column" ).sortable( "toArray" );           
            $.post( "../sort1.php",{ 'choices[]': sorted});  
        }
    });

PHP:

<?php
    $data = $_POST["choices"];  
    $filename = 'sort.txt';
    $handle = fopen($filename, "w");    
    foreach ($data as $value) {
    // Execute statement:
    // UPDATE [Table] SET [Position] = $i WHERE [EntityId] = $value
    fwrite($handle, $value."\n");

}
    fclose($handle);    
?>