Techartifact

The task is to parse a XML file retrieved from the RSS feed.
Below is the sample partial XML file taken from a Leading Geographical alerts website’s RSS feeds.

<?xml version="1.0" encoding="ISO-8859-1"?> 
<rss version="2.0" xmlns:geo="http://www.w3.org/2003/01/geo/"> 
<channel> 
<pubDate>Fri, 4 Jan 2008 09:51 GMT+1</pubDate> 

<item> 

<title>Red alert: Tropical Cyclone SINLAKU-08.</title> 
<description>Tropical Cyclone SINLAKU-08 .</description> 
<pubDate>Tue, 16 Sep 2008 06:00 GMT+1</pubDate> 
<geo:point> 
<geo:lat>27</geo:lat> 
<geo:long>124</geo:long> 
</geo:point> 
</item> 
<item> 

<title>Red alert: Tropical Cyclone IKE-08 .</title> 
<description>Tropical Cyclone IKE-08 .</description> 
<pubDate>Sun, 14 Sep 2008 09:00 GMT+1</pubDate> 
<geo:point> 
<geo:lat>36.400001526</geo:lat> 
<geo:long>-92.5</geo:long> 
</geo:point> 
</item> 

</channel> 
</rss>

As we can we there are two items(alerts) in the file one for Tropical Cyclone SINLAKU-08 and other for Tropical Cyclone IKE-08.

Lets write the code in c# to extract title,latitude and longitude of both the alerts.

First of all, lets load the XML data into the XMLDocument instance.

//include namespace for working with xml files
using System.Xml;
public partial class GoogleMap : System.Web.UI.Page
{
//creating new instance of xml document
XmlDocument xmlDoc = new XmlDocument();
protected void Page_Load(object sender, EventArgs e)
{
xmlDoc.Load(Server.MapPath(“~/XML Files/sourceRssEDIS.xml”));
//rest of the code described later will also be added here
}
}

Now, introduce the namespaces used in the xml file to the xmlDoc with the XmlNamespaceManager class instance.

XmlNamespaceManager nsMgr = new XmlNamespaceManager(xmlDoc.NameTable);
nsMgr.AddNamespace(“geo”, “http://www.w3.org/2003/01/geo/”);

Select all the items in a array using GetElementsByTagName() method.

XmlNodeList nodes = xmlDoc.GetElementsByTagName(“item”);

Iterate for the elements inthe nodes array using for loop and select the latitude and longitude values using SelectNodes() method as shown below and then set the values of text of respective labels.

for (int i = 0; i

Problem:
How to pass values into a usercontrol as querystrings in asp.net.
More References to the problem as as follows:

• Pass querystring to user control?
• Pass QueryString as Integer to UserControl

Solution:

1. One Can definitely use Session Variables to give the functionality. Set the session variable value in the page and then retrieve the value in the user control.
2. Another way is to set the Public Property for the userControl.
3. And one solution is described below which i implemented successfully. It also works for dynamically loaded usercontrol.

The Alternative New Method:

Method is simple:

1. Add Invisible buttons(or label) to the user control on the page where it will be rendered.
2. Set the text property of the buttons to the value of the querystring.

   UserControl mycontrol = new UserControl();
   mycontrol = (UserControl)Page.LoadControl(“./UserControls/CustomCallDetailsChart.ascx”);

   Button btnName=new Button();
   btnName.Visible = false;
   btnName.Text=this.Name;
   mycontrol.Controls.AddAt(0, btnName);

   this.Controls.Add(mycontrol);

3. In the page load event of the usercontrol find the control and typecast the text value to the required datatype.
   protected void Page_Load(object sender, EventArgs e)
   {
   Button btnName = (Button)this.Controls[0];
   this.ChartName = btnName.Text.ToString();
   }