Question

I am trying to delete a user from an Active Directory group via code. Getting the helpful error of:

Exception has been thrown by the targe
of an invocation”

Trace: Stack Trace: at
System.DirectoryServices.DirectoryEntry.Invoke(String
methodName, Object[] args) at
Active_Directory.RemoveUserFromGroup(String
sInUserName, String sInGroupName) in
C:\Documents and Settings\user\My
Documents\Visual Studio
2010\WebSites\appname\App_Code\Common\Active_Directory.vb:line
192

here is my function:

Check out the Invoke Line: oGroup.Invoke(“Remove”, New Object() {oUser.Path})

Public Shared Sub RemoveUserFromGroup(ByVal sInUserName As String _
                                      , ByVal sInGroupName As String)
    Dim entry1 As DirectoryEntry
    Dim de As DirectoryEntry
    Dim deSearch As DirectorySearcher
    Dim results As SearchResult
    Dim comeon As String
    Dim oUser As DirectoryEntry
    Dim oGroup As DirectoryEntry
    Dim sr As SearchResult

    Try

        entry1 = New DirectoryEntry("LDAP://rootDSE")
        comeon = entry1.Properties("DefaultNamingContext").Item(0)
        de = New DirectoryEntry("LDAP://" & comeon)

        deSearch = New DirectorySearcher()
        deSearch.SearchRoot = de
        deSearch.Filter = "(sAMAccountName=" + sInUserName + ")"
        deSearch.PropertiesToLoad.Add("cn")
        sr = deSearch.FindOne()

        If sr Is Nothing Then
            oUser = Nothing
        Else
            oUser = sr.GetDirectoryEntry()
        End If

        deSearch.Dispose()
        deSearch = Nothing
        sr = Nothing

        If Not (oUser Is Nothing) Then

            deSearch = New DirectorySearcher()
            deSearch.SearchRoot = de
            deSearch.Filter = "(&(objectClass=group) (CN=" & sInGroupName & "))"
            deSearch.SearchScope = SearchScope.Subtree

            results = deSearch.FindOne()

            If results IsNot Nothing Then

                oGroup = results.GetDirectoryEntry()

                Try

                    oGroup.Invoke("Remove", New Object() {oUser.Path})
                    oGroup.CommitChanges()
                    oGroup.Close()

                Catch ex As Exception
                    Dim s As String
                    s = ex.ToString
                    s = ""
                End Try

            End If

            entry1.Dispose()
            de.Dispose()

            entry1 = Nothing
            de = Nothing
            deSearch = Nothing
            results = Nothing

        End If

        oUser.Close()

    Catch ex As Exception

        Dim myerror As New MyError
        myerror.showMeTheError(ex)

    End Try

End Sub

Answer 1

You seem to be doing it extremely complicated – unnecessarily so.

Check out the Howto do almost everything in Active Directory CodeProject article – excellent stuff.

Here’s the snippet needed to remove a user (given by his DN) from a group (also defined by the DN):

public void RemoveUserFromGroup(string userDn, string groupDn)
{
    try
    {
        DirectoryEntry dirEntry = new DirectoryEntry("LDAP://" + groupDn);
        dirEntry.Properties["member"].Remove(userDn);
        dirEntry.CommitChanges();
        dirEntry.Close();
    }
    catch (System.DirectoryServices.DirectoryServicesCOMException E)
    {
        //doSomething with E.Message.ToString();

    }
}

Does that work for you??