How to add a Windows account to Security Group in a claims based SharePoint 2010 environment

In a timer job I added users to a certain SPGroup and added this group to some libraries with contribute rights. When I logged is with that user account it didn’t have the contribute rights. The problem was that the Windows account was added instead of the claims based user.

At first I just used the following code:

   1: String loginName = "SP2010\user1";

   2: SPGroup group = web.SiteGroups["somegroup"];

   3:  

   4: SPUser user = web.EnsureUser(loginName);

   5: if (user != null)

   6: {

   7:   group.AddUser(user);

   8: }

However this added a user as formatted in this XML:

<User ID="442" Sid="S-1-5-21-4190988674-4107964418-2216591577-1137" Name="Some name" LoginName="SP2010\user1" Email="test@test.com" Notes="" IsSiteAdmin="False" IsDomainGroup="False" Flags="0" />

I changed it to look for the correct SPUser using this code snippet:

   1: String loginName = "SP2010\user1";

   2:  

   3: SPClaimProviderManager mgr = SPClaimProviderManager.Local;

   4: if (mgr != null)

   5: {

   6:   SPClaim claim = new SPClaim(SPClaimTypes.UserLogonName, loginName, "http://www.w3.org/2001/XMLSchema#string", SPOriginalIssuers.Format(SPOriginalIssuerType.Windows));

   7:   claimLoginName = mgr.EncodeClaim(claim);

   8: }

   9:  

  10:  

  11: SPGroup group = web.SiteGroups["somegroup"];

  12: SPUser user = web.EnsureUser(claimLoginName);

  13: if (user != null)

  14: {

  15:   group.AddUser(user);

  16: }

This will generate a claim that represents the windows account “SP2010\user1”. This will find the correct SPUser, the XML is:

<User ID="255" Sid="" Name="Some name" LoginName="i:0#.w|SP2010\user1" Email="test@test.com" Notes="" IsSiteAdmin="False" IsDomainGroup="False" Flags="0" />

Notice the formatting of the LoginName.

Now the correct user account (in claims format) is added to the library with contribute rights the user logging in with SP2010\user1 can contribute.