PHP
Example - AJAX and XML
AJAX can be
used for interactive communication with an XML file.
AJAX XML
Example
The
following example will demonstrate how a web page can fetch information from an
XML file with AJAX:
Example
CD info will
be listed here...
Example
Explained - The HTML Page
When a user
selects a CD in the dropdown list above, a function called "showCD()"
is executed. The function is triggered by the "onchange" event:
<html>
<head>
<script>
function
showCD(str) {
if (str=="") {
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest) {
// code for IE7+, Firefox, Chrome, Opera,
Safari
xmlhttp=new XMLHttpRequest();
} else {
// code for IE6, IE5
xmlhttp=new
ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function() {
if (this.readyState==4 &&
this.status==200) {
document.getElementById("txtHint").innerHTML=this.responseText;
}
}
xmlhttp.open("GET","getcd.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>
<form>
Select
a CD:
<select
name="cds" onchange="showCD(this.value)">
<option
value="">Select a CD:</option>
<option
value="Bob Dylan">Bob Dylan</option>
<option
value="Bee Gees">Bee Gees</option>
<option
value="Cat Stevens">Cat Stevens</option>
</select>
</form>
<div
id="txtHint"><b>CD info will be listed
here...</b></div>
</body>
</html>
The showCD()
function does the following:
Check if a
CD is selected
Create an
XMLHttpRequest object
Create the
function to be executed when the server response is ready
Send the
request off to a file on the server
Notice that
a parameter (q) is added to the URL (with the content of the dropdown list)
The PHP File
The page on
the server called by the JavaScript above is a PHP file called "getcd.php".
The PHP
script loads an XML document, "cd_catalog.xml", runs a query against
the XML file, and returns the result as HTML:
<?php
$q=$_GET["q"];
$xmlDoc
= new DOMDocument();
$xmlDoc->load("cd_catalog.xml");
$x=$xmlDoc->getElementsByTagName('ARTIST');
for
($i=0; $i<=$x->length-1; $i++) {
//Process only element nodes
if ($x->item($i)->nodeType==1) {
if
($x->item($i)->childNodes->item(0)->nodeValue == $q) {
$y=($x->item($i)->parentNode);
}
}
}
$cd=($y->childNodes);
for
($i=0;$i<$cd->length;$i++) {
//Process only element nodes
if ($cd->item($i)->nodeType==1) {
echo("<b>" .
$cd->item($i)->nodeName . ":</b> ");
echo($cd->item($i)->childNodes->item(0)->nodeValue);
echo("<br>");
}
}
?>
When the CD
query is sent from the JavaScript to the PHP page, the following happens:
PHP creates
an XML DOM object
Find all
<artist> elements that matches the name sent from the JavaScript
Output the
album information (send to the "txtHint" placeholder)
