Checking login user role in razor page

Answer 1

Dave's answer is correct. I would suggest that you consider using a property on your model called IsAdministrator or CanSeeSidebar and treat answering that question as domain logic.

The view should work only with the model. Looking at the thread, reading from a database, are the same in respect that they answer domain questions. All those types of questions should be answered before your controller hands the model off to the view.