如何使用Dom php更改xml中的特定节点值

Question

Hi i want to change the value of cost to $6.0 where the color of cupcake is Red. how can i achieve that..here is my two sample cupcake though i have many cupcake in my xml file..so i want to first find the cupcake whose color is red and then change the corresponding cupcake price to whatever i like..

<cupcake>
    <name> Cookies and Cream</name>
    <flavours>
        <ingredient>Chocolate Cake</ingredient>
        <ingredient>Salted Caramel Buttercream</ingredient>
        <ingredient>Buttercream</ingredient>
    </flavours>
    <colors>
        <color>Red</color>
    </colors>
    <energy>1900.6Cal</energy>
    <cost>$22.50</cost>
</cupcake>

<cupcake>
    <name> Killer Carrot</name>
    <flavours>
        <ingredient>Carrot Spice cake</ingredient>
        <ingredient>Cream Cheese Frosting</ingredient>
        <ingredient>Candied Carrots</ingredient>
        <ingredient>Chocolate</ingredient>
    </flavours>
    <colors>
        <color>Aqua</color>
    </colors>
    <energy>1500.0KJ</energy>
    <cost>$15.80</cost>
</cupcake>

and my php file is

<?php
$xml = new DOMDocument();  
$xml->load('cupcakes.xml');  
if ($xml->schemaValidate('cupcakes.xsd')==FALSE)     
die ('<div class="error">Validation failed</div>'); 
$xsl = new DOMDocument(); 
$xsl->load('cupcakes.xsl'); 
$proc = new XSLTProcessor(); 
$proc->importStyleSheet($xsl); // attach the xsl rules  
echo $proc->transformToXML($xml);
echo "<hr/>";

echo "<h2> the first cupcake having color red has changed the cost value to $6.0"; 

$a = $xml->getElementsByTagName('color');
foreach ($a->nodeValue as $A){
if ($A = "Red")
$a->getElementsByTagName('cost')->nodeValue="$6.00";
}

echo $proc->transformToXML($xml); 
?>

Answer 1

You XML is missing a document element. It is not a valid XML file.

DOMNode::getElementsByTagName() returns a node list, not a single node. $nodeValue is a property of DOMNode , not DOMNodeList . Just checking the color value, will not do it. A cupcake can have several colors. If you use XPath you can have conditions like that:

$document = new DOMDocument();
$document->load($xmlFile);
$xpath = new DOMXpath($document);

foreach ($xpath->evaluate('//cupcake[colors/color = "Red"]/cost') as $cost) {
  $cost->nodeValue = '';
  $cost->appendChild($document->createTextNode('$6.00'));
}

echo $document->saveXml();

Output:

<?xml version="1.0"?>
<cupcakes>
<cupcake>
    <name> Cookies and Cream</name>
    <flavours>
        <ingredient>Chocolate Cake</ingredient>
        <ingredient>Salted Caramel Buttercream</ingredient>
        <ingredient>Buttercream</ingredient>
    </flavours>
    <colors>
        <color>Red</color>
    </colors>
    <energy>1900.6Cal</energy>
    <cost>$6.00</cost>
</cupcake>

<cupcake>
    <name> Killer Carrot</name>
    <flavours>
        <ingredient>Carrot Spice cake</ingredient>
        <ingredient>Cream Cheese Frosting</ingredient>
        <ingredient>Candied Carrots</ingredient>
        <ingredient>Chocolate</ingredient>
    </flavours>
    <colors>
        <color>Aqua</color>
    </colors>
    <energy>1500.0KJ</energy>
    <cost>$15.80</cost>
</cupcake>
</cupcakes>

XPath allows you to fetch nodes and scalar values. It this case:

Fetch all cupcake nodes...
//cupcake

... with a color node that equals "Red"...
//cupcake[colors/color = "Red"]

...and get its cost child node:
//cupcake[colors/color = "Red"]/cost

Answer 2

Tell us, what is wrong with your code, what is the error message if any...

and I suggest you try better the simpleXML usage since the syntax of it is way easier (to me). Here is a link you might check http://php.net/manual/en/simplexml.examples-basic.php

The syntax you use in your example resembles the js one. but you can you use a more easy one in php