XML/XPath: Difference between revisions
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// Create a XPathDocument object (which implements the IXPathNavigable interface) |
// Create a XPathDocument object (which implements the IXPathNavigable interface) |
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// which is optimized for XPath operation. (very fast). |
// which is optimized for XPath operation. (very fast). |
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Revision as of 10:02, 23 January 2007
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>
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" )
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; }
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);