WebGrid with custom paging and sorting in ASP.NET MVC

public class ModelServices : IDisposable
{
 private readonly TestDBEntities entities = new TestDBEntities();
 
 //For Custom Paging
 public IEnumerable<Customer> GetCustomerPage(int pageNumber, int pageSize, string sort, bool Dir)
 {
 if (pageNumber < 1)
 pageNumber = 1;
 
 if (sort == "name")
 return entities.Customers.OrderByWithDirection(x => x.Name, Dir)
 .Skip((pageNumber - 1) * pageSize)
 .Take(pageSize)
 .ToList();
 else if (sort == "address")
 return entities.Customers.OrderByWithDirection(x => x.Address, Dir)
 .Skip((pageNumber - 1) * pageSize)
 .Take(pageSize)
 .ToList();
 else if (sort == "contactno")
 return entities.Customers.OrderByWithDirection(x => x.ContactNo, Dir)
 .Skip((pageNumber - 1) * pageSize)
 .Take(pageSize)
 .ToList();
 else
 return entities.Customers.OrderByWithDirection(x => x.CustID, Dir)
 .Skip((pageNumber - 1) * pageSize)
 .Take(pageSize)
 .ToList();
 }
 public int CountCustomer()
 {
 return entities.Customers.Count();
 }
 
 public void Dispose()
 {
 entities.Dispose();
 }
}

public class PagedCustomerModel
{
 public int TotalRows { get; set; }
 public IEnumerable<Customer> Customer { get; set; }
 public int PageSize { get; set; }
} 

public static class SortExtension
{
 public static IOrderedEnumerable OrderByWithDirection
 (this IEnumerable source,Func keySelector,bool descending)
 {
 return descending ? source.OrderByDescending(keySelector)
 : source.OrderBy(keySelector);
 }
 
 public static IOrderedQueryable OrderByWithDirection
 (this IQueryable source,Expression> keySelector,bool descending)
 {
 return descending ? source.OrderByDescending(keySelector)
 : source.OrderBy(keySelector);
 }
}

    

@model Mvc4_CustomWebGrid.Models.PagedCustomerModel
@{
 ViewBag.Title = "WebGrid with Custom Paging, Sorting";
 WebGrid grid = new WebGrid(rowsPerPage: Model.PageSize);
 grid.Bind(Model.Customer,
 autoSortAndPage: false,
 rowCount: Model.TotalRows); 
}

@grid.GetHtml(
 fillEmptyRows: false,
 alternatingRowStyle: "alternate-row",
 headerStyle: "grid-header",
 footerStyle: "grid-footer",
 mode: WebGridPagerModes.All,
 firstText: "<< First",
 previousText: "< Prev",
 nextText: "Next >",
 lastText: "Last >>",
 columns: new[] {
 grid.Column("CustID",header: "ID", canSort: false),
 grid.Column("Name"),
 grid.Column("Address"),
 grid.Column("ContactNo",header: "Contact No")
 }
)

public class HomeController : Controller
{
 ModelServices mobjModel = new ModelServices();
 
 public ActionResult WebGridCustomPaging(int page = 1, string sort = "custid", string sortDir = "ASC")
 {
 const int pageSize = 5;
 var totalRows = mobjModel.CountCustomer();
 
 bool Dir = sortDir.Equals("desc", StringComparison.CurrentCultureIgnoreCase) ? true : false;
 
 var customer = mobjModel.GetCustomerPage(page, pageSize, sort, Dir);
 var data = new PagedCustomerModel()
 {
 TotalRows = totalRows,
 PageSize = pageSize,
 Customer = customer
 };
 return View(data);
 }
}