How to make a Cascading Drop Down List in PHP using jQuery

$("#country").change(function(){
    $('#city').find('option').remove().end(); //clear the city ddl
    var country = $(this).find("option:selected").text();
    alert(country);
    //do the ajax call
    $.ajax({
        url:'getCity.php'
        type:'GET',
        data:{city:country},
        dataType:'json',
        cache:false,
        success:function(data){

        data=JSON.parse(data); //no need if dataType is set to json
         var ddl = document.getElementById('city');                      

         for(var c=0;c<obj.length;c++)
              {              
               var option = document.createElement('option');
               option.value = obj[c];
               option.text  = obj[c];                           
               ddl.appendChild(option);
              }


    },
        error:function(jxhr){
        alert(jxhr.responseText);

    }
    }); 

});

in your getCity.php

$country = $_GET['city'];

//do the db query here

$query  = "your query";
$result = mysql_query($query);
$temp = array();
while ($row = mysql_fetch_assoc($result)) {

 if(empty($temp))
 {
   $temp=array($row['city']);
 }
 else
 {  
   array_push($temp,$row['city']);
 }

}
echo (json_encode($temp));

The session information is a resource that can only be used exclusively, and you have not taken this into account.

Specifically, under default settings session_start causes PHP to acquire an exclusive lock on a file that contains the session data. This file is not unlocked until the script exits or session_write_close is called.

In your example, process.php acquires the lock and starts working. In the meantime, progress.php tries to session_start() and cannot (due to the lock). Enough time needs to pass for process.php to complete and exit (thus releasing the lock) before the request for progress information can be satisfied.

A small change you can make that will have immediate effect is to call session_write_close and session_start from within your worker loop:

for ($i=0; $i <= $totalItems; $i++) {
    session_start();
    $_SESSION['currentItem'] = $i;
    $_SESSION['percentComplete'] = round(($i / $totalItems * 100));
    session_write_close();
}

This will allow the two scripts to take turns locking the session storage file, so you will see things working as intended. However, performance will tank (this is a really impolite way to treat the session storage file).

If you had need to do something like this in the real world, it would be necessary to utilize something other than the session data to enable this exchange of information between the PHP scripts (e.g. an in-memory cache like APC or memcached).

It's creating a multi-select because one rfq can have many standards, so it allows you to ctrl-click to select many standards.

You could try adding :input_html => { :size =>'1' } but I'm not sure that will preserve the scrollbar. It definitely won't drop down.

Here's someone else who wanted to do the same thing: HTML muliple select should look like HTML select. One of the answers refers to a Dropdown Check List implemented in jQuery, but that would take some work to integrate with SimpleForm.

SimpleForm has a very helpful Google Group--you might get more ideas there:

http://groups.google.com/group/plataformatec-simpleform