How to Retrieve Content from Wikipedia using C#

A college friend is currently developing a University Library system which is connected to internet. The system has kiosks for student to search for books they want to borrow. For example, if a students type-in Manny pacquiao on the search box, it should display all available books or magazines about Manny. Aside books result, the system should also be able to extract some information/biography about Manny. We thought that instead of populating a information database, the system will just retrieve contents from a public encyclopedia database such as Wikipedia.


Luckily for him wikipedia has a readily available API for this kind of web request. To show how we did it using C#, I created a sample project for you that can be downloaded from Mediafire.

Just follow these steps to create your own from scractch:
1. Create a new Project on your C# IDE.
2. On the form, Add a button and a richtextbox (textbox will do)
3. Double click the form to show the coding window. Add the following namespaces at the Using directives.

using System.Net;
using System.IO;
using System.Xml;
using System.Xml.XPath;

4. Now double click the button to show the coding window then on the click event paste the following code:

private void btnRetrieve_Click(object sender, EventArgs e)
{
HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create("http://en.wikipedia.org/wiki/Special:Export/Manny_Pacquiao");
webRequest.Credentials = System.Net.CredentialCache.DefaultCredentials;
webRequest.Accept = "text/xml";
try
{
HttpWebResponse webResponse = (HttpWebResponse)webRequest.GetResponse();
Stream responseStream = webResponse.GetResponseStream();
XmlReader xmlreader = new XmlTextReader(responseStream);
String NS = "http://www.mediawiki.org/xml/export-0.3/";
XPathDocument xpathdoc = new XPathDocument(xmlreader);
xmlreader.Close();
webResponse.Close();
XPathNavigator myXPathNavigator = xpathdoc.CreateNavigator();
XPathNodeIterator nodesIt = myXPathNavigator.SelectDescendants("text", NS, false);

while (nodesIt.MoveNext())
{
rtWikiContent.AppendText(nodesIt.Current.InnerXml);
}
}
catch (Exception ex)
{
MessageBox.Show("Error while retrieve from Wikipedia. " + ex.ToString());
}
}

5. Now lets test the application. Clicking the retrieve button should display a result like this.



If you want to try the Visual Studio 2005 project included with this post, download it here.

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