Display Headlines From an RSS Feed on Your Website (ASP.NET)

Category:

C#, VB.NET, ASP.NET

Type:

Snippets

Difficulty:

Intermediate

Author:

Intelligent Solutions Inc.

Version Compatibility: ASP.NET

More information:

This is an ASP.NET version of the ASP function at http://www.freevbcode.com/ShowCode.Asp?ID=5665 . It allows you to display RSS syndicated feeds on your web site. The content of each feed is cached for an hour, using the built-in ASP.NET cache object. You have to change the code in Page_Load to the URL of the feed you want to use.

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
' (None)

Code:

<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Xml" %>
<script language="VB" runat="server">
Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

'Some implementations of rss do not use description,
        'some do
        'so we check to see if description is a column, if not
        'use an alternative dataset

'alternatively, you can autogenerate columns and
        'display whatever columns the feed contains. But
        'most contain fields that are not intended for display,
        'so I prefer not to do it that way.

Dim oDGToUse, odgNotToUse As DataGrid
        Dim oDT As DataTable
  	dim i as integer
        'change the URL as you desire
        'you can find many RSS feeds at
        'http://www.syndic8.com

Response.Write("Slashdot Latest Headlines:<p>")
        oDT = GetRSSFeed("http://slashdot.org/slashdot.rdf", "SlastDot")
    
        If Not oDT Is Nothing Then
            oDGToUse = IIf(oDT.Columns.Contains("description"), _
                  datagrid1,datagrid2)
            odgNotToUse = IIf(oDT.Columns.Contains("description"), _
                    datagrid2, datagrid1)
            oDGToUse.Visible = True
            odgNotToUse.Visible = False

oDGToUse.DataSource = oDT
            oDGToUse.AutoGenerateColumns = False
            oDGToUse.DataBind()

Else
            Response.Write("Could not retrieve requested feed")
        End If
    End Sub

Function GetRSSFeed(ByVal rssURL As String, ByVal FeedTitle As String) _
  As DataTable
        'LOGIC:
        'get xml from remote ur and convert to dataset
        'place into cache for an hour using ASP.nET
        'built-in cache object
        'set to expire in an hour

Dim oDT As DataTable

If Cache(FeedTitle) Is Nothing Then
            Try
                Dim reader As XmlTextReader = New XmlTextReader(rssURL)

Dim ds As DataSet = New DataSet
                ds.ReadXml(reader)

Cache.Insert(FeedTitle, ds.Tables(2), Nothing,DateTime.Now.AddHours(1), TimeSpan.Zero)
                oDT = ds.Tables(2)
            Catch
                If Not Cache(FeedTitle) Is Nothing Then oDT =Cache(FeedTitle)
            End Try
        Else
            If Not Cache(FeedTitle) Is Nothing Then oDT = Cache(FeedTitle)
        End If

Return oDT

End Function
</script>

</asp:datagrid> <p>
<asp:DataGrid runat="server" id="Datagrid2">
<ItemStyle VerticalAlign="Top">
</itemstyle>

</asp:datagrid>
</p>
    </form>