ASP.net , C#: Bind a Yahoo RSS Feed to a Gridview

I will go over this code in a minute. But, before I do that, I just want to go over the declarative way of doing this. Which is much easier and simpler to implement than this approach. After that we will go over your code as well. This would give us a better idea of different ways of doing the same thing in ASP .NET

i) Add XMLDATASOURCE control and configure it like this:
  Data File: Use RSS Feed URL from Yahoo
  Transform: Leave blank
  XPath: type in: rss/channel/item

ii) Add DataList control and configure it to use XMLDATASOURCE
iii) In source view, find DataList control and add this code
<itemtemplate>
<asp:hyperlink navigateUrl="<%#XPath("link")%>" text="<%#XPath("title")%>" />
</itemtemplate>

Now, run your page. THe datalist would be populated with RSS feeds. The output would be hyperlinks with text and link to follow.

Let me know if you are still interested in going over your code above. If so, I can check it up. Otherwise, the code above would fulfill most rss read requirements.

rafayali:

I have and do retrieve most of my XML RSS like you have explained, however I need to do some data minpulation and more complitated stuff before I send it to my Grid..

Can you show me how to do it in the code behind and than place in a <itemtemplate>

Yes, here is some sample code that I took from one of the projects I did in the past. It reads xml data source at builder.com and retrieves all values through code using DOM.

Basically, I am using SelectNodes and provide an XPATH expression to retrieve all items under channel which are under rss tag. Then I iterate through the returned values and retrieve title and links and dynamically create hyperlinks.

Let me know if this helps in any way.

 Dim myXMLDOC As New XmlDocument()
        myXMLDOC.Load("http://www.builderau.com.au/feeds/features.htm")
        Dim xmlNode As XmlNode
        Dim xmllist As XmlNodeList
        xmllist = myXMLDOC.SelectNodes("rss/channel/item")
        For Each xmlNode In xmllist
            Dim titlenode As XmlNode
            Dim linknode As XmlNode
            titlenode = xmlNode.SelectSingleNode("title")
            linknode = xmlNode.SelectSingleNode("link")
            Dim myhyperlink As New HyperLink
            myhyperlink.NavigateUrl = linknode.InnerText
            myhyperlink.Text = titlenode.InnerText & "<br/><br/>"
            myhyperlink.Attributes.Add("style", "color:#336699;font-size:12px;font-family:Arial;a:hover{color:red;background-color:yellow}")
            
            placeholder1.Controls.Add(myhyperlink)
        Next
    End Sub

Select allOpen in new window

rafayali:

I'm a newbie at this can you show me this in C#, and than place in a <itemtemplate>

<itemtemplate> is only used if you are binding using declarative syntax; that is, syntax in the source view of the aspx page (that is mixed with html).

I have shown you an alternate programming only approach since you had mentioned you wanted to achieve more than what the functionality of the controls provided for. This way you have complete control over what is output to the client.

I am not too familiar with C#. Therefore, conversion is a bit tricky for me here. However, I will provide you with logic of each line of my code. Hopefully, then you can convert it to C#. If not, let me know I can have a friend convert it to C#. But, it should be pretty straightforward.

Here is the explanation

i) Declare an object named myXMLDOC which is an instantiation of XMLDOCUMENT class in the System.XML namespace

ii) load the URL of RSS into this object. This line WOULD STAY THE SAME IN C# i think

iii) Declare variable named xmlNode of type XMLNODE

iv) Declare variable named xmllist of type XMLNODELIST

v) In xmllist, store values that are returned after call to SelecNodes method of myXMLDOC object. myXMLDOC.SelectNodes("rss/channel/item") would probably stay as is in C#.

vi) Go over the collection stored in xmllist using For each loop of VB. You might have a similar loop in C#.

vii) Inside the loop declare variable named titleNode that is oftype xmlnode

vii) Inside the loop declare variable named linkNode which is of type xmlnode

viii) Inside the loop, store return value of xmlNode.SelectSingleNode("title") in titlenode variable

ix) Inside the loop, store return value of xmlNode.SelectSingleNode("link") in linknode variable

x) Create a new hyperlink object

xi) Use hyperlinks navigateURL property and assign the innertext of linknode to that

xii) Use hyperlinks text property and assign the innertext property of titlenode to that

xiii) Next line just adds some styling to hyperlink. You can omit that if you want

xiv) Add the control to the placeholder control. The placeholder control should be on your webform and the id of placeholder should be placeholder1. You can ofcourse change this, but the code looks for this id.

xv) Close the loop

Hopefully you can translate this into C#.

Since all CODE in ASP.NET is run in response to a trigger of some event, you can either place this code in LOAD event of Page object (Page_Load), or make this into a function (method) and call this wherever you want.

Let me know if you were able to translate it into C#. Otherwise, I will go over some C# tutorial and try to convert it for you. If anything, it would help me start up with C# :) So let me know.

All the data manipulation can be done via this code and XMLDOCUMENT class. What and how exactly do you want to manipulate the RSS feed?

Dim myXMLDOC As New XmlDocument()
 
        myXMLDOC.Load("http://www.builderau.com.au/feeds/features.htm")
        Dim xmlNode As XmlNode
        Dim xmllist As XmlNodeList
        xmllist = myXMLDOC.SelectNodes("rss/channel/item")
        For Each xmlNode In xmllist
            Dim titlenode As XmlNode
            Dim linknode As XmlNode
            titlenode = xmlNode.SelectSingleNode("title")
            linknode = xmlNode.SelectSingleNode("link")
            Dim myhyperlink As New HyperLink
            myhyperlink.NavigateUrl = linknode.InnerText
            myhyperlink.Text = titlenode.InnerText & "<br/><br/>"
            myhyperlink.Attributes.Add("style", "color:#336699;font-size:12px;font-family:Arial;a:hover{color:red;background-color:yellow}")
            
            placeholder1.Controls.Add(myhyperlink)
        Next
    End Sub

Select allOpen in new window

What is happening here, I believe, is that dataset's readxml method is creating a datatable for each level of nesting in the RSS XML file. Therefore, if you want to experiemnt further change tables(3) to tables(4),tables(5), tables(6) and see that the result varies. Therefore, try experimenting with it. I have come to the conclusion that this is what is happening in this case because clearly there are more than one data table even though nothing of this sort was specified in the code.

And, to show only a particular column such as only title column in the gridview use this code inside gridview

<Columns>
        <asp:TemplateField>
       
        <ItemTemplate>
              <%# DataBinder.Eval(Container.DataItem, "title") %>
        </ItemTemplate></asp:TemplateField></Columns>

This should be between <asp:gridview></asp:gridview tags>

To further enhance this you can also place this in the itemtemplate instead

 <ItemTemplate>
       
       <asp:HyperLink ID="HyperLink1" NavigateUrl=<%#DataBinder.Eval(Container.DataItem,"link") %> runat="server"><%#DataBinder.Eval(Container.DataItem,"title") %>
       </asp:HyperLink>
       </ItemTemplate>

Let me know if this helped or you needed some other thing?