public async Task <IActionResult> OnGetAsync(int?pairID)
{
await CheckRole(_context, _userManager, JoinCode);
if (pairID == null)
{
return(NotFound());
}
var id = pairID.GetValueOrDefault();
var pair = await _context.GetPairAsync(id);
Courses = pair.Courses;
JoinCode = pair.JoinCode;
return(Page());
}