get data in ajax

[eluser][email protected][/eluser]
hi guys can someone help me. i'm trying to call the data that passes through this ajax method.
how can i get data in controller?

Thanks a lot

Code:

$( "#sortable" ).sortable({
                update: function(){
                
                            stringDiv = "";
                            $("#sortable").children().each(function(i) {
                              var li = $(this);
                             if(li.attr("class") == "ui-state-default"){
                              stringDiv += " "+li.attr("id") + '=' + i + '&';
                              }
                            });
                            
                             $.ajax({
                               type: "POST",
                               url: "<?=base_url().'admin/updatelist/'?>",
                               data: stringDiv,
                               success: function(msg){
                                 $( "#dialog" ).dialog();
                                 console.log(stringDiv);
                                    // [removed].reload( true );
                               }
                             });

                        }

            });