Tuesday, February 2, 2010

Using Microsoft.SharePoint.dll to find out the ID of a list

When moving a site between web applications using SharePoint Designer backup (Site > Administration > Backup Web Site menu), several web parts wich had been converted to XSLT were displaying a "strange" message:

The server returned a non-specific error when trying to get data from the data source. Check the format and content of your query and try again. If the problem persists, contact the server administrator.

When an web part is converted to XSLT, SharePoint Designer places on the page a control of type WebPartPages:DataFormWebPart to display the data. This control uses the list ID to specify wich list is the data source (each list in a SharePoint site is given a GUID as its identifier, wich is stored in the list's ID property). Well, when the site was recreated at the destination, so were its lists, and that generated new ID's to them. And the web parts could not find their lists anymore, so they stopped working.

Being a restless geek, I decided to test the classes on Microsoft.SharePoint.dll by coding a little console app that listed the ID's from a SharePoint site lists. The code is bellow, and can be used as an intro to classes in namespace Microsoft.SharePoint. If you want just the app, just download the following file and run it from a command prompt on your SharePoint machine: SPListId.zip.

Imports Microsoft.SharePoint

Module Module1

Sub Main()
If My.Application.CommandLineArgs.Count = 0 Then
Console.WriteLine("SPListId - Lists IDs from lists in a SharePoint site")
Console.WriteLine("Copyright (c) 2010 SrNimbus. No rights reserved ;)")
Console.WriteLine("Usage: SPListId site_url")
End If
' The System.Uri class helps manipulating network addresses
Dim urlSite As Uri = New Uri(My.Application.CommandLineArgs(0))
' The Microsoft.SharePoint.SPSite class represents a site collection on SharePoint
Dim siteCollection As New SPSite(urlSite.GetComponents(UriComponents.SchemeAndServer, UriFormat.Unescaped))
' The Microsoft.SharePoint.SPWeb class represents a site on a site collection
Dim site As SPWeb = siteCollection.OpenWeb(urlSite.AbsolutePath)
Console.WriteLine("Lists on {0}:", urlSite.OriginalString)
' The SPList class represents a SharePoint list
For Each lista As SPList In site.Lists
Console.WriteLine("{0}: {{{1}}}", lista.Title, lista.ID.ToString().ToUpper())
Catch erro As Exception
Console.WriteLine("{0} - {1}", erro.Source, erro.Message)
End Try
End Sub

End Module

Remember to add a reference to Microsoft.SharePoint.dll in order to compile the project. It is located on the SharePoint server, at %ProgramFiles%\Common Files\Microsoft Shared\Web Server Extensions\12\ISAPI.

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