Article discussion for:
Building an RSS feed made simple

Jeff 'Jones' Putz
POP World Media, LLC
Maximizing ASP.NET

Quick question for you. How difficult would it be to implement an RSS feed with the Pop Forum, like it's done at Asp.Net?

Jeff 'Jones' Putz
POP World Media, LLC
Maximizing ASP.NET

[InvalidCastException: Specified cast is not valid.]   System.Data.SqlClient.SqlDataReader.GetSqlDateTime(Int32 i) +46   System.Data.SqlClient.SqlDataReader.GetDateTime(Int32 i) +33   admin.cstain.RSS.newsfeed.Page_Load(Object sender, EventArgs e) in c:\inetpub\wwwroot\v2\newsfeed.aspx.vb:38   System.Web.UI.Control.OnLoad(EventArgs e) +67   System.Web.UI.Control.LoadRecursive() +35   System.Web.UI.Page.ProcessRequestMain() +731

I am fairly new to asp.net from what I can gather this is happening on the time formatting. I am still unsure of all of the formatting options (one page i viewed show 17 examples alone and there are still more) so I am just lost of how to correct this. When I save the timestamp in my database i just use the standard formatting of the now command. which is m/d/yy 00:00:00 AM/PM I seen you were using R as your formatting type. I am unsure if that is the format you are saving it in your database or if you are reformatting your data to the R type. If you could help me I would appreciate it. I have also incluided the code I used on the page.

Imports System

Imports System.Configuration

Imports System.Data

Imports System.Data.SqlClient

Imports System.Text

Imports System.Web

Imports System.Xml

Namespace cstain.RSS

Public Class newsfeed

Inherits System.Web.UI.Page

Private Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

Response.Clear()

Response.ContentType = "text/xml"

Dim objX As New XmlTextWriter(Response.OutputStream, Encoding.UTF8)

objX.WriteStartDocument()

objX.WriteStartElement("rss")

objX.WriteAttributeString("version", "2.0")

objX.WriteStartElement("channel")

objX.WriteElementString("title", "Crimson Stain Productions")

objX.WriteElementString("link", "http://www.crimsonstain.net/newsfeed.aspx")

objX.WriteElementString("description", "The latest in what going on with Crimson Stain Productions")

objX.WriteElementString("copyright", "(c) 2004, Crimson Stain Productions, All rights reserved.")

objX.WriteElementString("ttl", "5")

Dim objConnection As New SqlConnection(ConfigurationSettings.AppSettings("MyConnectionString"))

objConnection.Open()

Dim sql As String = "SELECT TOP 10 title, main, postid, time FROM cstain_news ORDER BY time DESC"

Dim objCommand As New SqlCommand(sql, objConnection)

Dim objReader As SqlDataReader = objCommand.ExecuteReader()

While objReader.Read()

objX.WriteStartElement("item")

objX.WriteElementString("title", objReader.GetString(0))

objX.WriteElementString("description", objReader.GetString(1))

objX.WriteElementString("link", "http://www.crimsonstain.net/GetArticle.aspx?id=" + objReader.GetInt32(2).ToString())

objX.WriteElementString("pubDate", objReader.GetDateTime(3).ToString("G"))

objX.WriteEndElement()

End While

objReader.Close()

objConnection.Close()

objX.WriteEndElement()

objX.WriteEndElement()

objX.WriteEndDocument()

objX.Flush()

objX.Close()

Response.End()

End Sub

End Class

End Namespace

Thanks,

Mike

objX.WriteElementString("pubDate", objReader.GetDateTime(3).ToString("G"))

Are you using a non-US version of SQL Server and/or the server OS? Are you absolutely sure that your "time" column is the type datetime?

Jeff 'Jones' Putz
POP World Media, LLC
Maximizing ASP.NET

Jeff 'Jones' Putz
POP World Media, LLC
Maximizing ASP.NET

Many thanks Jeff,

This is just what I was looking for. Had it up and running in no time. Now I just have to see if any of my customers use it!

Regards
Mark

Great Article - I'm trying to get it to work with a news database I'm using and keep getting an XML Parsing Error: no element found

Imports System
Imports System.Configuration
Imports System.Data
Imports System.Data.SqlClient
Imports System.Text
Imports System.Web
Imports System.Xml

Namespace LMC.RSS
Public Class NewsWire
Inherits System.Web.UI.Page
Private Sub Page_Load(sender As Object, e As System.EventArgs)
Response.Clear()
Response.ContentType = "text/xml"
Dim objX As New XmlTextWriter(Response.OutputStream, Encoding.UTF8)
objX.WriteStartDocument()
objX.WriteStartElement("rss")
objX.WriteAttributeString("version", "2.0")
objX.WriteStartElement("channel")
objX.WriteElementString("title", "LMC.Net NewsWire")
objX.WriteElementString("link", "http://www.lemoyne.edu/rss/rss.aspx")
objX.WriteElementString("description", "The latest headlines and events from around le Moyne College")
objX.WriteElementString("copyright", "(c) 2006 Le Moyne College. All rights reserved.")
objX.WriteElementString("ttl", "20")
Dim objConnection As New SqlConnection(ConfigurationSettings.AppSettings("MyConnectionString"))
objConnection.Open()
Dim sql As String = "SELECT TOP 20 NewsHeadline, NewsDetails, NewsNo, NewsExpDate FROM DailyNews ORDER BY NewsExpDate DESC"
Dim objCommand As New SqlCommand(sql, objConnection)
Dim objReader As SqlDataReader = objCommand.ExecuteReader()
While objReader.Read()
objX.WriteStartElement("item")
objX.WriteElementString("title", objReader.GetString(0))
objX.WriteElementString("description", objReader.GetString(1))
objX.WriteElementString("link", "/rss/GetArticle.aspx?id=" + objReader.GetInt32(2).ToString())
objX.WriteElementString("pubDate", objReader.GetDateTime(3).ToString("R"))
objX.WriteEndElement()
End While
objReader.Close()
objConnection.Close()
objX.WriteEndElement()
objX.WriteEndElement()
objX.WriteEndDocument()
objX.Flush()
objX.Close()
Response.End()
End Sub
End Class
End Namespace

Any suggestions as to what I've done wrong would be appreciated!

What line does the error occur on?

Jeff 'Jones' Putz
POP World Media, LLC
Maximizing ASP.NET

in my rss.aspx page, it says its occurring in line 1 position 1

Wow, I'm not sure. Your code looks like a straight port from my C# code, and I know that works (it's on this site's feed!).

Jeff 'Jones' Putz
POP World Media, LLC
Maximizing ASP.NET

Is this truly the directory structure? And, is the code you posted your code? If so, a few questions. First of all, you're trying to write VB code in a C# file. That's probably your error.

Beyond that, have you complied? Etc...

d8

The cause of the problem is:
The POP server is out of Coke .

Hi,

I have a question about the c# RSS Feed code. This will sound strange, but I implemented it, it all seemed fine, validated it OK, and I subscribed it into Newscrawler to test. It loaded fine, but when I close and reopen Newscrawler, they all disappear - read and unread. I try to hit update - nothing happens. This doesnt happen with other feeds I added. Any ideas?

Thanks in advance

Tim

No idea. Sounds like more of an issue with the reader. I've used many different readers without issue. You never can tell for sure when you don't have control of that side of the equation.

Jeff 'Jones' Putz
POP World Media, LLC
Maximizing ASP.NET

Thanks Jeff,

I think I've sorted it. When validating it, the validator told me to switch Coding to ASCII from UTF8 to match my server, but I think this was responsible. I switched it to UTF8 and doesn't happen anymore, so there you go, strange.

Tim

Thanks for the code JEFF! As a hack programmer who
does not do .net work but inherited a .net site , I had problems with this statement.

SqlConnection objConnection = new SqlConnection(ConfigurationSettings.AppSettings["MyConnectionString"]);

Time and research helped me figure this out but it might help newbies like me if a tutorial existed for this. No pressure and it may already exist on the site. By help I mean using a fictious DB on a SQL Server with fake login and password so we replace the variables, atleast for a direct connection to the DB.

Another issue was dealing with .net 2.0, from my limited knowledge, your code would be problematic in a 2.0 environment. Is that right? I understand why, 2.0 did not exist when you wrote it.

To get around that, I made use of this guy's code, looks like a 2.0 version of your code, and pass it along for anyone else that may need it.

http://forums.asp.net/thread/1314507.aspx

go to the 11-06-2006, 10:41 AM response.

Thanks again for the code, big big help!

The code works exactly the same in 2.0. I think if you compile or build you'll get a warning for a couple of things that have been deprecated, but they'll still work just fine. v2 has a web.config section for connection strings all its own.

Jeff 'Jones' Putz
POP World Media, LLC
Maximizing ASP.NET