UserPrincipal extensions returns computers

Question

I'm pretty new to active directory and I'm currently working on a library for a project to easily manage our active directory objects like users, resources, groups and so on.

The library is in .NetStandard 2.0 and I use the Principal classes from

System.DirectoryServices.AccountManagement

As the UserPrincipal class doesn't contain all the properties that we could need, I tried to implement an UserPrincipalExtended class that, for now, just add the Initials property.

Here is my class :

[DirectoryObjectClass("user")]
[DirectoryRdnPrefix("CN")]
public class UserPrincipalExtended : UserPrincipal
{
    public UserPrincipalExtended(PrincipalContext context) : base(context) { }

    public UserPrincipalExtended(PrincipalContext context, string samAccountName, string password, bool enabled) : base(context, samAccountName, password, enabled) { }

    [DirectoryProperty("Initials")]
    public string Initials
    {
        get
        {
            if (ExtensionGet("initials").Length != 1) return null;

            return (string)ExtensionGet("initials")[0];

        }
        set { ExtensionSet("initials", value); }
    }

    public static new UserPrincipalExtended FindByIdentity(PrincipalContext context, string identityValue)
    {
        return (UserPrincipalExtended)FindByIdentityWithType(context, typeof(UserPrincipalExtended), identityValue);
    }

    public static new UserPrincipalExtended FindByIdentity(PrincipalContext context, IdentityType identityType, string identityValue)
    {
        return (UserPrincipalExtended)FindByIdentityWithType(context, typeof(UserPrincipalExtended), identityType, identityValue);
    }
}

When I do a search in the active directory using the UserPrincipal class, it works as expected :

using (var context = _contextProvider.GetPrincipalContext())
using (var query = new UserPrincipal(context))
using (var searcher = new PrincipalSearcher(query))
{
    foreach (var principal in searcher.FindAll())
    {
        UserPrincipal userPrincipal = principal as UserPrincipal;

        if (CheckHelper.IsFilled(userPrincipal))
        {
            Console.WriteLine($"{userPrincipal.StructuralObjectClass} : {userPrincipal.SamAccountName}");
        }
    }
}

/*Output
user : cadmin
user : Guest
user : DefaultAccount
*/

But if I try to perform the same search using my own class, the result contains also computers :

using (var context = _contextProvider.GetPrincipalContext())
using (var query = new UserPrincipalExtended(context))
using (var searcher = new PrincipalSearcher(query))
{
    foreach (var principal in searcher.FindAll())
    {
        UserPrincipalExtended userPrincipalExtended = principal as UserPrincipalExtended;

        if (CheckHelper.IsFilled(userPrincipalExtended))
        {
            Console.WriteLine($"userPrincipalExtended.StructuralObjectClass} : {userPrincipalExtended.SamAccountName}");
        }
    }
}
/*Output
user : cadmin
user : Guest
user : DefaultAccount
computer : WS001$
computer : WS002$
computer : WS003$
*/

As my UserPrincipalExtended class has the attribute :

[DirectoryObjectClass("user")]

I thought that was enough to filter on this object type in the active directory, but it seems it does not.

Any idea of what's going on here?

Cheers

Answer 1

microsoft Principal types filter creating code

Also faced with this problem.Having rummaged in the source code, I found such a workaround.

[DirectoryObjectClass("user)(objectCategory=user")]