Update a Select with onchange of other Select

[eluser]abmcr[/eluser]
The php code in a view

Code:

$js = 'onChange="get_dati_gerachia()"';
echo form_dropdown('dati_gerarchia', $options, "TRUE",$js);echo "\n";
.....
    $id = 'id="master" ';
            $options = array(
                              'y'  => 'Master',
                              'n'  => 'Normale'
                            );
            echo "<span id='ajax_target'>".form_dropdown('master', $options,'',$id)."</span>";

and the js routine

Code:

function get_dati_gerachia(){
    var chosenItemText = $("select[name='dati_gerarchia']").val();
     a="data="+chosenItemText;
     $.ajax({
      type: "POST",
      url:  "<?php echo site_url("the_url_of_your_ajax_controller")?>",
      data: a,
      success: function(msg){
        $("#ajax_target").html(msg);
        }
    });
}

and your ajax controller

Code:

function the_url_of_your_ajax_controller(){
        $var=$this->input->post("data");
..... some operations and build your select dependency
$html="<select......."
echo $html;
}

Into this the_url_of_your_ajax_controller you build the second select and echo to the ajax_target div