public IActionResult Filter(string filter, int?pagenumber)
{
float minprice = float.Parse(filter.Substring(filter.IndexOf('đ') + 1, filter.IndexOf(' ') - 1));
float maxprice = float.Parse(filter.Substring(filter.LastIndexOf('đ') + 1));
pageNumber = pagenumber ?? 1;
SanPhamBUS sanphambus = new SanPhamBUS();
List <SanPham> list = sanphambus.Filter(minprice, maxprice, pageSize, pageNumber);
List <SanPham> tong = sanphambus.Filter(minprice, maxprice);
ViewBag.TrangHienTai = pageNumber;
ViewBag.TongTrang = TongTrang(tong);
ViewBag.TrangThai = "filter";
ViewBag.Filter = filter;
List <HangSanPham> hang = ctx.HangSanPham.ToList();
ViewBag.Hang = hang;
return(View("List", list));
}