XML/XPath: Difference between revisions
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{{task}}
Perform the following three XPath queries on the XML Document below:
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</cfsavecontent>
<cfset xml = xmlParse(xmlString)>
<!--- First Task --->
<cfset itemSearch = xmlSearch(xml, "//item")>
<!--- item = the first Item (xml element object) --->
<cfset item = itemSearch[1]>
<!--- Second Task --->
<cfset priceSearch = xmlSearch(xml, "//price")>
<!--- loop and print each price --->
<cfloop from="1" to="#arrayLen(priceSearch)#" index="i">
#priceSearch[i].xmlText#<br/>
</cfloop>
<!--- Third Task --->
<!--- array of all the name elements --->
<cfset names = xmlSearch(xml, "//name")>
<!--- 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" )
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Revision as of 19:24, 26 August 2007
![Task](http://static.miraheze.org/rosettacodewiki/thumb/b/ba/Rcode-button-task-crushed.png/64px-Rcode-button-task-crushed.png)
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)> <!--- First Task ---> <cfset itemSearch = xmlSearch(xml, "//item")> <!--- item = the first Item (xml element object) ---> <cfset item = itemSearch[1]> <!--- Second Task ---> <cfset priceSearch = xmlSearch(xml, "//price")> <!--- loop and print each price ---> <cfloop from="1" to="#arrayLen(priceSearch)#" index="i"> #priceSearch[i].xmlText#<br/> </cfloop> <!--- Third Task ---> <!--- array of all the name elements ---> <cfset names = xmlSearch(xml, "//name")> <!--- visualize the results ---> <cfdump var="#variables#">
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
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
<?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
#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" )