How to query in an async method?

Hi,

I want to filter the database by the id:

 public async Task<IActionResult> Index(int? id)
        {
            var viewModel = new ShopIndexData()
            {
                Categories = await _context.Category
                .Include(c => c.ShopAssignments)
                .Include(s => s.ShopSortAssignment)
                .AsNoTracking()
                .ToListAsync()
            };
            return View(viewModel);

        }

How do I do that?

Poul Erik