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PHP AJAX and XML instance

AJAX can be used to communicate interactively with the XML file.


AJAX XML instance

The following examples will demonstrate how a web page via AJAX reading information from an XML file:

Examples


CD info will be listed here...



Examples explain - HTML page

When a user in the above drop-down list to select a Double CD, it performs named "showCD ()" function. This function by the "onchange" event is triggered:

<html>
<head>
<script>
function showCD(str)
{
	if (str=="")
	{
		document.getElementById("txtHint").innerHTML="";
		return;
	} 
	if (window.XMLHttpRequest)
	{
		// IE7+, Firefox, Chrome, Opera, Safari 浏览器执行
		xmlhttp=new XMLHttpRequest();
	}
	else
	{
		// IE6, IE5 浏览器执行
		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 whether the CD is selected
  • Create XMLHttpRequest object
  • Create function when the server is ready to perform the response
  • File on the server to send requests
  • Please note added to the end of the URL parameter (q) (contains the contents of the drop-down list)

PHP File

The above servers through JavaScript calling this page is called "getcd.php" PHP file.

PHP script to load an XML document, " cd_catalog.xml ", to run queries against 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; $i++)
{
	// 处理元素节点
	if ($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++)
{ 
	// 处理元素节点
	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 JavaScript to PHP page will occur:

  1. PHP create XML DOM object
  2. Find all <artist> element with JavaScript preached data matching names
  3. Output album information, and sends back "txtHint" placeholder