XML/XPath: Difference between revisions

From Rosetta Code
< XML
Content added Content deleted
(Perl)
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</cfsavecontent>
</cfsavecontent>
<cfset xml = xmlParse(xmlString)>
<cfset xml = xmlParse(xmlString)>
&lt;!--- First Task --->
<cfset itemSearch = xmlSearch(xml, "//item")>
&lt;!--- item = the first Item (xml element object) --->
<cfset item = itemSearch[1]>
&lt;!--- Second Task --->
<cfset priceSearch = xmlSearch(xml, "//price")>
&lt;!--- loop and print each price --->
<cfloop from="1" to="#arrayLen(priceSearch)#" index="i">
#priceSearch[i].xmlText#&lt;br/>
</cfloop>
&lt;!--- Third Task --->
&lt;!--- array of all the name elements --->
<cfset names = xmlSearch(xml, "//name")>
&lt;!--- visualize the results --->
<cfdump var="#variables#">

==[[JavaScript]]==
[[Category:JavaScript]]

'''Interpreter:''' Firefox 2.0

//create XMLDocument object from file
var xhr = new XMLHttpRequest();
xhr.open('GET', 'file.xml', false);
xhr.send(null);
var doc = xhr.responseXML;
//get first <item> element
var firstItem = doc.evaluate( '//item[1]', doc, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null ).singleNodeValue;
alert( firstItem.textContent );
//output contents of <price> elements
var prices = doc.evaluate( '//price', doc, null, XPathResult.ANY_TYPE, null );
for( var price = prices.iterateNext(); price != null; price = prices.iterateNext() ) {
alert( price.textContent );
}
//add <name> elements to array
var names = doc.evaluate( '//name', doc, null, XPathResult.ANY_TYPE, null);
var namesArray = [];
for( var name = names.iterateNext(); name != null; name = names.iterateNext() ) {
namesArray.push( name );
}
alert( namesArray );

Although some browsers support XPath, working with XML is much easier with E4X.

//create XML object from file
var xhr = new XMLHttpRequest();
xhr.open('GET', 'file.xml', false);
xhr.send(null);
var doc = new XML(xhr.responseText);
//get first <item> element
var firstItem = doc..item[0];
alert( firstItem );
//output contents of <price> elements
for each( var price in doc..price ) {
alert( price );
}
//add <name> elements to array
var names = [];
for each( var name in doc..name ) {
names.push( name );
}
alert( names );

==[[Perl]]==
[[Category:Perl]]
use XML::XPath qw();
my $x = XML::XPath->new('<inventory ... </inventory>');
[$x->findnodes('//item[1]')->get_nodelist]->[0];
print $x->findnodes_as_string('//price');
$x->findnodes('//name')->get_nodelist;

==[[PHP]]==
[[Category:PHP]]
<?php
//PHP5 only example due to changes in XML extensions between version 4 and 5 (Tested on PHP5.2.0)
$doc = DOMDocument::loadXML('<inventory title="OmniCorp Store #45x10^3">...</inventory>');
//Load from file instead with $doc = DOMDocument::load('filename');
$xpath = new DOMXPath($doc);
/*
1st Task: Retrieve the first "item" element
*/
$nodelist = $xpath->query('//item');
$result = $nodelist->item(0);
/*
2nd task: Perform an action on each "price" element (print it out)
*/
$nodelist = $xpath->query('//price');
for($i = 0; $i < $nodelist->length; $i++)
{
//print each price element in the DOMNodeList instance, $nodelist, as text/xml followed by a newline
print $doc->saveXML($nodelist->item($i))."\n";
}
/*
3rd Task: Get an array of all the "name" elements
*/
$nodelist = $xpath->query('//name');
//our array to hold all the name elements, though in practice you'd probably not need to do this and simply use the DOMNodeList
$result = array();
//a different way of iterating through the DOMNodeList
foreach($nodelist as $node)
{
$result[] = $node;
}

==[[Ruby]]==
[[Category:Ruby]]
#Example taken from the REXML tutorial (http://www.germane-software.com/software/rexml/docs/tutorial.html)
require "rexml/document"
include REXML
#create the REXML Document from the string (%q is Ruby's multiline string, everything between the two @-characters is the string)
doc = Document.new(
%q@<inventory title="OmniCorp Store #45x10^3">
...
</inventory>
@
)
# The invisibility cream is the first <item>
invisibility = XPath.first( doc, "//item" )
# Prints out all of the prices
XPath.each( doc, "//price") { |element| puts element.text }
# Gets an array of all of the "name" elements in the document.
names = XPath.match( doc, "//name" )

Revision as of 08:34, 12 June 2007

Task
XML/XPath
You are encouraged to solve this task according to the task description, using any language you may know.

Perform the following three XPath queries on the XML Document below:

  • Retrieve the first "item" element
  • Perform an action on each "price" element (print it out)
  • Get an array of all the "name" elements

XML Document: 

<inventory title="OmniCorp Store #45x10^3">
  

    <item upc="123456789" stock="12">
      <name>Invisibility Cream</name>
      <price>14.50</price>
      <description>Makes you invisible</description>
    </item>
    <item upc="445322344" stock="18">
      <name>Levitation Salve</name>
      <price>23.99</price>
      <description>Levitate yourself for up to 3 hours per application</description>
    </item>
  

  

    <item upc="485672034" stock="653">
      <name>Blork and Freen Instameal</name>
      <price>4.95</price>
      <description>A tasty meal in a tablet; just add water</description>
    </item>
    <item upc="132957764" stock="44">
      <name>Grob winglets</name>
      <price>3.56</price>
      <description>Tender winglets of Grob. Just add water</description>
    </item>
  

</inventory>

C#

 XmlReader XReader;

 // Either read the xml from a string ...
 XReader = XmlReader.Create(new StringReader("<inventory title=... </inventory>"));

 // ... or read it from the file system.
 XReader = XmlReader.Create("xmlfile.xml");

 // Create a XPathDocument object (which implements the IXPathNavigable interface)
 // which is optimized for XPath operation. (very fast).
 IXPathNavigable XDocument = new XPathDocument(XReader);

 // Create a Navigator to navigate through the document.
 XPathNavigator Nav = XDocument.CreateNavigator();
 Nav = Nav.SelectSingleNode("//item");

 // Move to the first element of the selection. (if available).
 if(Nav.MoveToFirst())
 {
   Console.WriteLine(Nav.OuterXml); // The outer xml of the first item element.
 }

 // Get an iterator to loop over multiple selected nodes.
 XPathNodeIterator Iterator = XDocument.CreateNavigator().Select("//price");

 while (Iterator.MoveNext())
 {
   Console.WriteLine(Iterator.Current.Value);
 }

 Iterator = XDocument.CreateNavigator().Select("//name");

 // Use a generic list.
 List<string> NodesValues = new List<string>();

 while (Iterator.MoveNext())
 {
   NodesValues.Add(Iterator.Current.Value);
 }

 // Convert the generic list to an array and output the count of items.
 Console.WriteLine(NodesValues.ToArray().Length);

ColdFusion

 <cfsavecontent variable="xmlString">
 <inventory
 ...
 </inventory>
 </cfsavecontent>
 <cfset xml = xmlParse(xmlString)>
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