Determine "normal" Users from User Collection loaded with CSOM (provider-hosted App)

Question

In my provider-hosted app I load the UserCollection from SharePoint by CSOM (Client Side Object Model), like this:

UserCollection users = web.SiteUsers;
clientContext.Load<UserCollection>(users);
clientContext.ExecuteQuery();

But I only want "normal" users to be displayed in my app. The result given here also shows users which seem to be system users, like:

• _SPOCacheFull
• System Account
• Everyone
• Everyone except external users

How can I determine if a user is a normal site user or a system user?

I checked the groups but most of the system users don't have any groups. Also the email is mostly empty but not always.

Answer 1

The following User properties could be used for that purpose:

• Principal.PrincipalType property - PrincipalType.User value specifies a user as the principal type
• UserIdInfo.NameIdIssuer property - configuration-agnostic reference to the type of the name identifier issuer, for SPO users its value: urn:federation:microsoftonline

The below example demonstrates how to determine a "regular" users in Web.SiteUsers:

public static IEnumerable<User> LoadUsers(ClientContext context)
{
   var users = context.LoadQuery(context.Web.SiteUsers.Where(u => u.PrincipalType == PrincipalType.User && u.UserId.NameIdIssuer == "urn:federation:microsoftonline"));
   context.ExecuteQuery();
   return users;
}