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PHP Example - AJAX and XML


AJAX can be used to interactively communicate with XML files.


AJAX XML example

The following example demonstrates how a web page can read information from an XML file via AJAX:

Example

Example


CD data will be recorded here...

Example explanation-HTML page

When the user selects a CD in the drop-down list above, a function named "showCD ()" is executed. This function is triggered by the "onchange" event:

<html>
<head>
<script>
function showCD(str)
{
    if (str=="")
    {
        document.getElementById("txtHint").innerHTML="";
        return;
    } 
    if (window.XMLHttpRequest)
    {
        //IE7+, Firefox, Chrome, Opera, Safari Browser execution
        xmlhttp=new XMLHttpRequest();
    }
    else
    {
        //IE6, IE5 Browser execution
        xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
    }
    xmlhttp.onreadystatechange=function()
    {
        if (xmlhttp.readyState==4 && xmlhttp.status==200)
        {
            document.getElementById("txtHint").innerHTML=xmlhttp.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="Bonnie Tyler">Bonnie Tyler</option>
<option value="Dolly Parton">Dolly Parton</option>
</select>
</form>
<div id="txtHint"><b>CD info will be listed here...</b></div>

</body>
</html>

showCD () function performs the following steps:

  • Check if a CD is selected
  • Creating an XMLHttpRequest object
  • Create a function to be executed when the server response is ready
  • Send a request to a file on the server
  • Please note the parameter (q) added to the end of the URL (including the content of the drop-down list)

PHP file

The above server page called via JavaScript is a PHP file named "getcd.php".

<?php
$q=$_GET["q"];

$xmlDoc = new DOMDocument();
$xmlDoc->load("cd_catalog.xml");

$x=$xmlDoc->getElementsByTagName('ARTIST');

for ($i=0; $i<=$x->length-1; $i++)
{
    //Processing element nodes
    if ($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++)
{ 
    //Processing 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 a CD query is sent from JavaScript to a PHP page, it will happen:

  1. PHP creates XML DOM objects
  2. Find all <artist> The name of the element that matches the data passed by JavaScript
  3. Output information from album and send it back to "txtHint" placeholder