Acquiring all roles an authenticated user has in

Question

I'm trying to load an authenticated user's roles, since I need the data in every page I thought it best to add the code in _Layout.cshtml.

@using Microsoft.AspNetCore.Identity

<header>
@{
if (User.Identity.IsAuthenticated)
{
UserManager<IdentityUser> userManager = new UserManager<User>();

var rolesArray = userManager.GetRolesAsync(User.Identity.??);
}
}
</header>

But I can't seem to find out how exactly I can do that in the given context.

Can anyone here help?

PS: This might not be the best solution, but since I'm rather new @ this I would like to continue in this direction for the time being