Checking login user role in razor page

Solution 1:

@if (Request.IsAuthenticated && User.IsInRole("Administrators"))
{
     <div id="sidebar">
        <div class="module">
           <ul class="menu">
              <li>@Html.ActionLink("Home", "Index", "Home")</li>
              <li>@Html.ActionLink("About", "About", "Home")</li>
              <li>@Html.ActionLink("Contact", "Contact", "Home")</li>
            </ul>
         </div>
         <div class="mainContent">
             Hello, @User.Identity.Name !
         </div>
     </div>
}

Solution 2:

For ASP.NET Core Razor Pages

if (User.Identity.IsAuthenticated && User.IsInRole("Administrator"))

Solution 3:

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.