XPath / Grabbing node values in Code Behind RSS

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  HVMDesign

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  2 Posts

  XPath / Grabbing node values in Code Behind

  Nov 29, 2012 08:30 PM|LINK

  Hello,

  I am fairly new to ASP.NET (PHP programmer for 8 years), so please forgive me if my terminology is incorrect.

  I am currently grabbing a remote XML file in a repeater XMLDataSource, and the DataFile attribute is being set in the code behind (I have the DateFile dynamically change based on URI paramaters such as ?cat=blah etc). This works beautifully and is not a problem.

  Within this repeater is a<asp:HyperLink>, whose URL is to be dynamically changed in the code behind as well.

  Now to the question:
  From the code behind, how can I see if XML nodes are empty, and how can I grab the value of nodes that are not, so I can alter the <asp.Hyperlink> URL so it contains that value?

  I have been on this issue for about 3 days now (hours of searching), however I just cannot figure out something that seems like it should be so simple! Here is the code I currently have, however I am given an error of Object reference not set to an instance of an object for the code behind line that has CreateNavigator();

  Hopefully somebody more adept than me with ASP.NET and C# can easily spot the problem or knows of a way I can accomplish this?

  THANK YOU!

  Code:

  <asp:XmlDataSource ID="rssFeed" runat="server"></asp:XmlDataSource>
  <asp:Repeater runat="server" DataSourceID="rssFeed" OnItemDataBound="Repeater_ItemDataBound">
  	<ItemTemplate>
  		<asp:HyperLink ID="articleURL" Text='<%#XPath("title")%>' runat="server" />
  	</ItemTemplate>
  </asp:Repeater>

  Code Behind C#:

  	protected void Page_Load(object sender, EventArgs e)
  	{
  		// rss variables
  		var rssSource = "http://websiteurl.com/xmlfeed/";
  		var rssPath = "rss/channel/item";
  		var searchQueries = "?foo=bar";
  		string currCat = Request.QueryString["cat"];
  		string searchTerms = Request.QueryString["s"];
  
  		// insert categories query
  		if(currCat != null){
  			searchQueries += "&cat=" + Request.QueryString["cat"];
  		}
  
  		// insert search query
  		if(searchTerms != null){
  			searchQueries += "&s=" + searchTerms;
  		}
  
  		// load RSS file
  		rssFeed.DataFile = rssSource + searchQueries;
  		rssFeed.XPath = rssPath;
  	}
  
  	// return message if results are empty
  	protected void Repeater_ItemDataBound(object sender, RepeaterItemEventArgs e)
  	{
  		XPathNavigator nav = ((IXPathNavigable)e.Item.DataItem).CreateNavigator();
  		string hyperlinkURL = nav.SelectSingleNode("link").Value;
  		// removed code here that changes URL to hyperlinkURL to shorten post
   }

  
  
  
  

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  HVMDesign

  0 Points

  2 Posts

  Re: XPath / Grabbing node values in Code Behind

  Nov 30, 2012 08:43 PM|LINK

  For those who may be interested in this as well, I found a solution where I can easily check and manipulate xml items.

  Code Behind C#

  protected void Repeater_ItemDataBound(object sender, RepeaterItemEventArgs e)
  {
  	// make sure we are not checking item in ItemHeader or ItemFooter to prevent null value
  	if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem) {
  		string myVar = XPathBinder.Eval(e.Item.DataItem,"title").ToString();
  
  		// utilize and manipulate myVar XML value here
  	}
  }

  
  
  

  • Marked as answer by HVMDesign on Nov 30, 2012 08:43 PM