{"id":581,"date":"2007-07-06T16:45:05","date_gmt":"2007-07-06T15:45:05","guid":{"rendered":"http:\/\/www.craigmurphy.com\/blog\/?p=581"},"modified":"2007-07-06T16:59:24","modified_gmt":"2007-07-06T15:59:24","slug":"net-xml-and-xpath","status":"publish","type":"post","link":"http:\/\/www.craigmurphy.com\/blog\/?p=581","title":{"rendered":".NET – XML and XPath"},"content":{"rendered":"

I have been receiving a few requests for my now elderly Delphi XML\/XPath<\/a> examples to be brought into the world of .NET. Similarly, I have seen a lot of newsgroup posts about using XML and XPath expressions, particularly those XPath expressions that can be used to “query” the XML “database”.<\/p>\n

The most popular request seems to have been for my “employee” selector demonstration:<\/p>\n

<\/p>\n

It’s a small application that lets you load some XML (employee data) into an XML document. It then lets you fire a handful of XPath expressions at the XML document via the use of the SelectNode methods. It demonstrates selecting specific employees using a combination of conditions; there’s a mixture of XPath that looks at element values and one that looks at an attribute value. I’ve revamped it slightly, noteably I’ve made a few minor changes to bring it into line with current W3C standard (as enforced by .NET’s SelectNodes<\/a> method).<\/p>\n

[code lang=”XML”]
\n[XML]
\n
\n
\n
\nNelson<\/emp_lastname>
\nRoberto<\/emp_firstname>
\n250<\/emp_phoneext>
\n40000<\/emp_salary>
\n<\/employee><\/p>\n


\nYoung<\/emp_lastname>
\nBruce<\/emp_firstname>
\n233<\/emp_phoneext>
\n55500<\/emp_salary>
\n<\/employee>
\n…
\n<\/employees>
\n[\/code]<\/p>\n

[code lang=”C#”]
\n[C#]
\nusing System;
\nusing System.Collections.Generic;
\nusing System.ComponentModel;
\nusing System.Data;
\nusing System.Drawing;
\nusing System.Text;
\nusing System.Windows.Forms;<\/p>\n

using System.Xml;<\/p>\n

namespace XML
\n{
\n public partial class Form1 : Form
\n {
\n XmlDocument doc;<\/p>\n

public Form1()
\n {
\n InitializeComponent();
\n }<\/p>\n

private void button1_Click(object sender, EventArgs e)
\n {
\n doc = new XmlDocument();
\n doc.Load(“employees.xml”);<\/p>\n

textBox1.Text = doc.OuterXml;
\n }<\/p>\n

private void handle_xpath(String xPathExpression)
\n {
\n XmlNodeList result;
\n XmlNode root = doc.DocumentElement;<\/p>\n

result = root.SelectNodes(xPathExpression);<\/p>\n

label1.Text = String.Format(“{0} items returned”, result.Count);<\/p>\n

textBox3.Clear();
\n foreach (XmlNode x in result)
\n {
\n textBox3.Text = textBox3.Text + x.OuterXml + Environment.NewLine + Environment.NewLine;
\n }
\n }<\/p>\n

private void button2_Click(object sender, EventArgs e)
\n {
\n handle_xpath(“.\/\/employee”);
\n }<\/p>\n

private void button3_Click(object sender, EventArgs e)
\n {
\n handle_xpath(“\/employees”);
\n }<\/p>\n

private void button4_Click(object sender, EventArgs e)
\n {
\n handle_xpath(“\/employees\/employee[1]”);
\n }<\/p>\n

private void button5_Click(object sender, EventArgs e)
\n {
\n handle_xpath(“\/employees\/employee[last()]”);
\n }<\/p>\n

private void button6_Click(object sender, EventArgs e)
\n {
\n handle_xpath(“\/employees\/employee[emp_salary>30000 and emp_salary<35000]\");\n }\n\n private void button7_Click(object sender, EventArgs e)\n {\n handle_xpath(\"\/employees\/employee[emp_salary>30000 and emp_salary<35000 and emp_salary[@currency='UKP']]\");\n }\n\n private void button8_Click(object sender, EventArgs e)\n {\n handle_xpath(\"\/employees\/employee[emp_salary > 50000]\/emp_lastname”);
\n }<\/p>\n

private void button9_Click(object sender, EventArgs e)
\n {
\n handle_xpath(textBox2.Text);
\n }
\n }
\n}
\n[\/code]<\/p>\n

The source code is available here<\/a> [60k].<\/p>\n

There’s a short 60 second movie of the application in use here<\/a> [748kb]. Courtesy of TechSmith’s Camtasia<\/a>.<\/p>\n

Technorati Tags: XML<\/a>, XPath<\/a>, C#<\/a>, C-Sharp<\/a>, SelectNodes<\/a>, VS2005<\/a>, Visual Studio 2005<\/a>, Visual C# Express<\/a>, Camtasia<\/a>, TechSmith<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

I have been receiving a few requests for my now elderly Delphi XML\/XPath examples to be brought into the world of .NET. Similarly, I have seen a lot of newsgroup posts about using XML and XPath expressions, particularly those XPath expressions that can be used to “query” the XML “database”. The most popular request seems … Continue reading .NET – XML and XPath<\/span> →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15,3],"tags":[],"class_list":["post-581","post","type-post","status-publish","format-standard","hentry","category-net","category-development"],"_links":{"self":[{"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/581","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=581"}],"version-history":[{"count":0,"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/581\/revisions"}],"wp:attachment":[{"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=581"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=581"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.craigmurphy.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=581"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}