Create ASP.NET Syndication Feeds with SqlConnection and VB.NET

Question

This seems to be a great article by Scott Mitchell for creating syndicated feeds in ASP.NET 3.5. The problem for me is that it uses C# and Linq, which I'm not as sharp on at the current time.

http://dotnetslackers.com/articles/aspnet/How-to-create-a-syndication-feed-for-your-website.aspx

Does anyone know where an example might exist for the System.ServiceModel.Syndication namespace that can produce a syndicated feed like this article using VB.NET and a SQLConnection object?

I've looked around and every example seems to be produced in C# and Linq (which is probably a testament to my need to learn them soon rather than later).

Answer 1

You’ve probably figured it out by now, but here’s an implementation for completeness and some VB love (and an attempt for the Necromancer badge. :)

The aspx page is simple, note the 60 second cache:

<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="Default.aspx.vb" Inherits="YourProject._Default" %>
<%@ OutputCache Duration="60" VaryByParam="Type" %>

You probably want to consider using an HttpHandler instead, but this will work just fine too.

The code behind:

Imports System.ServiceModel.Syndication
Imports System.Xml

Partial Public Class _Default
  Inherits System.Web.UI.Page

  Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    Dim dbConn As String = "[your db connection]"
    Dim format As FeedFormats = GetFeedFormat()
    Dim posts As New List(Of SyndicationItem)

    Using cnn As New SqlClient.SqlConnection(dbConn)
      cnn.Open()

      Using cmd As New SqlClient.SqlCommand("SELECT ID, Title, Text, Url, Created FROM Posts", cnn)
        Dim reader As SqlClient.SqlDataReader = cmd.ExecuteReader

        While reader.Read
          Dim item As New SyndicationItem(reader.Item("Title"), reader("Text"), New Uri(reader("Url")))

          posts.Add(item)
        End While
      End Using
    End Using

    Dim feed As New SyndicationFeed("Your feed title", "Your feed description", New Uri("http://yourdomain.com"), posts)

    Using feedWriter As XmlWriter = XmlWriter.Create(Response.OutputStream)
      Select Case format
        Case FeedFormats.Atom
          Response.ContentType = "application/rss+xml"

          Dim atomFormatter As New Atom10FeedFormatter(feed)
          atomFormatter.WriteTo(feedWriter)
        Case FeedFormats.Rss
          Response.ContentType = "application/atom+xml"

          Dim rssFormatter As New Rss20FeedFormatter(feed)
          rssFormatter.WriteTo(feedWriter)
      End Select
    End Using
  End Sub

  Private Function GetFeedFormat() As FeedFormats
    If Request.QueryString("format") = "atom" Then
      Return FeedFormats.Atom
    Else
      Return FeedFormats.Rss
    End If
  End Function

  Public Enum FeedFormats
    Rss = 1
    Atom = 2
  End Enum
End Class

Finally, for super-completeness, the SQL script for creating the table:

CREATE TABLE [dbo].[Posts](
 [ID] [int] IDENTITY(1,1) NOT NULL,
 [Title] [nvarchar](50) NOT NULL,
 [Text] [ntext] NOT NULL,
 [Url] [nvarchar](50) NOT NULL,
 [Created] [datetime2](7) NOT NULL,
 CONSTRAINT [PK_Posts] PRIMARY KEY CLUSTERED 
(
 [ID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]

GO

ALTER TABLE [dbo].[Posts] ADD  CONSTRAINT [DF_Posts_Url]  DEFAULT ('') FOR [Url]
GO

ALTER TABLE [dbo].[Posts] ADD  CONSTRAINT [DF_Posts_Created]  DEFAULT (getdate()) FOR [Created]
GO

Done. VB.NET, a SQL Connection, the System.ServiceModel.Syndication namespace, and no LINQ. :)

Update: Got the Necromancer badge on 11-11-2010. Yay! Thanks! :)