Working with nested groups, it can be hard to determine if a user is member of the “base” group. The following class contains a method to do the job.

IsGroupMember ( GroupName, UserName ) calls method ExplodeGroup, which fills an array with all members of the group. It also resolves nested groups.

IsGroupMember now checks if the username is a member of this array using Lotusscript function ArrayGetIndex.

Class NotesDominoDirectory

	Private strServer As String

	Public Sub new (server As String )
		strServer = server
	End Sub

	Public Function ExplodeGroup (GroupName As String) As Variant

		Dim s As New Notessession
		Dim db As New NotesDatabase ( Me.strServer, "names.nsf" )
		Dim doc As NotesDocument
		Dim view As NotesView
		Dim i As Integer, j As Integer, k As Integer
		Dim arrGrp1, arrGrp2 As Variant

		Set view=Db.GetView ("($VIMGroups)")
		Set doc=View.GetDocumentByKey (GroupName)
		Redim arrMembers (1) As Variant
		j = 0

		If Not (doc Is Nothing) Then
			arrGrp1= Doc.GetItemValue ("Members")
			For i= 0 To Ubound (arrGrp1)
				arrGrp2= Me.ExplodeGroup (arrGrp1 (i))
				Redim Preserve arrMembers (Ubound (arrGrp2) + j) As Variant
				For k= 0  To Ubound (arrGrp2)
					arrMembers (j) = arrGrp2 (k)
					j = j + 1
				Next
			Next
		Else
			Redim arrMembers (0) As Variant
			arrMembers (0) = GroupName
		End If

		ExplodeGroup= Arrayunique (arrMembers)

	End Function 

	Public Function IsGroupMember ( strGroup As String, strUser As String ) As Boolean

		IsGroupMember = False

		If (Arraygetindex (Me.ExplodeGroup (strGroup), strUser , 5))  Then
			IsGroupMember = True
		End If

	End Function

	Public Function IsGroupMemberExt ( strGroup As String, strUser As String ) As Boolean
		' uses undocumented function
		Dim arrMembers As Variant
		IsGroupMemberExt = False
		arrMembers =
            Evaluate(|@ExpandNameList("|& strServer & |":"names.nsf";"|& strGroup &|")| )
		If (Arraygetindex ( arrMembers, strUser, 5)) Then
			IsGroupMemberExt = True
		End If
	End Function

End Class

Here is a sample of how to check if Ulrich Krause is member of group “Everybody”

Sub Click(Source As Button)
	Dim res As Variant
	Dim dd As New NotesDominoDirectory ("serv01/singultus")
	Msgbox dd.IsGroupMember ( "Everybody" , "CN=Ulrich Krause/O=singultus")
End Sub

There is also an undocumented @formula @ExpandNameList to expand a group and all nested groups to all the names.

Function IsGroupMemberExt ( strGroup As String, strUser As String ) As Boolean
	' uses undocumented function
	Dim arrMembers As Variant
	IsGroupMemberExt = False
	arrMembers =
         Evaluate(|@ExpandNameList("|& strServer &|":"names.nsf";"|& strGroup &|")| )
	If (Arraygetindex ( arrMembers, strUser, 5))  Then
	     IsGroupMemberExt = True
	End If
End Function