Can't figure out what's wrong with my variable passing

[MelindaM]

Hi guys, I'm new to PHP and AJAX/JS so I apologize if this is an incredibly obvious error.

I'm in the process of creating multiple listboxes that are chained together for an advanced search form. I have everything working for the ajax and the issue I'm running into is when I try to pass a PHP variable to a JS function. I've searched multiple forums and read multiple posts about this issue but cannot figure out what's going on. I know that everything else is working because if I pass in something besides my PHP variable things come out fine.

The method is called whenever the selection changes:
<select multiple size=5 name="Package" style="width: 15em;" onchange='setPackage($partType, this.value)'>

It's the "$partType" that I'm having issues with. I've tried passing it about a dozen different ways with no luck and I'm not sure how to debug the issue. The function is pretty basic:
function setPackage(str, blah)
{
....
}

Any advice would be appreciated.

-Melinda

[Dormilich]

try

setPackage(<?php echo $partType; ?>, this.value)

[MelindaM]

Thanks for the reply. I tried what you suggested and nothing happens when I select something in the listbox. If I change the code to pass in "this.value" for both params it works just fine so I'm not missing anything anywhere else that I know of.

Here's what the javascript looks like:

function setPackage(str, blah)
{
xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
  {
  alert ("Browser does not support HTTP Request");
  return;
  }
var url="getVendor.php?";
url=url+"package="+str;
url=url+"&partType="+blah;
url=url+"&sid="+Math.random();
xmlhttp.onreadystatechange=stateChanged2;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}
 
function stateChanged2()
{
if (xmlhttp.readyState==4)
{
document.getElementById("vendorSelect").innerHTML=xmlhttp.responseText;
}
}

and the PHP for it:

<?php require_once('../Connections/dev/admin.php'); ?>
<?php require_once('../Connections/dev/phtdeelib.php'); ?>
<?php
if(isset($_GET['partType'])) {
  echo "PartType = " . $_GET['partType'] . "<br>";
}
 
if(isset($_GET['package'])) {
  echo "Package = " . $_GET['package'] . "<br>";
}
 
?> 

Is there a way to debug it and see what's wrong with how the variable is being passed?

Thanks in advance!
-Melinda

[Dormilich]

@MelindaM
If you use Firefox and the Firebug Add-on, you can check the GET/POST requests in the network tab.

[MelindaM]

I just figured out that I can pass "this.form" instead and then in the method parse out all the values that I need, such as:

var val1=form.PartType.options[form.PartType.options.selectedIndex].value;
var val2=form.Package.options[form.Package.options.selectedIndex].value;

It only requires passing the one form variable instead of passing multiple values which will be better if this form gets very complex. Hopefully this is a good solution.

I'll probably still try to figure out what's going on the other way using Firebug because I want to understand why the original way won't work.

Thanks for the quick responses guys!
-Melinda