Question

I am new to both MVC and Stackoverflow I am trying to implement pagination for a MVC 3 project with a legacy database. I have worked my way through the tutorial at

http://www.asp.net/mvc/tutorials/getting-started-with-ef-using-mvc/sorting-filtering-and-paging-with-the-entity-framework-in-an-asp-net-mvc-application

but when I try to implement the pagination method it compiles but it does not run IE throws and error that reads

The method ‘Skip’ is only supported for sorted input in LINQ to Entities. The method ‘OrderBy’ must be called before the method ‘Skip’.

I tried putting skip before and after the orderby in the lines before the error but it still gives me the same error. I have posted my code below for my controller and the index. If anyone has seen this error before and can take a look at my code I would be extremely thankful.

PaController

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using DBFirstMVC.Models;
using System.Data;
using PagedList;
using PagedList.Mvc;

namespace DBFirstMVC.Controllers
{
    public class PaController : Controller
    {
        PaEntities db = new PaEntities();
        //
        // GET: /Pa/

        public ViewResult Index(string sortOrder, string currentFilter, string searchString, int? page)
        {
            ViewBag.CurrentSort = sortOrder;
            ViewBag.NameSortParm = String.IsNullOrEmpty(sortOrder) ? "PA desc" : "";

            if (Request.HttpMethod == "GET")
            {
                searchString = currentFilter;
            }
            else
            {
                page = 1;
            }
            ViewBag.CurrentFilter = searchString;


            var IAMP = from p in db.iamp_mapping select p;

            if (!String.IsNullOrEmpty(searchString))
            {
                IAMP = IAMP.Where(p => p.PA.ToUpper().Contains(searchString.ToUpper()));
            }

            switch (sortOrder)
            {
                case "Pa desc":
                    IAMP = IAMP.Skip(1).OrderByDescending(p => p.PA);
                    break;


                default:
                    IAMP.Skip(1).OrderBy(p => p.PA);
                    break;
            }
            int pageSize = 20;
            int pageNumber = (page ?? 1);

            return View(IAMP.ToPagedList(pageNumber, pageSize));
        }


        //
        // GET: /Pa/Details/5

        public ActionResult Details(int id)
        {
            return View();
        }

        //
        // GET: /Pa/Create

        public ActionResult Create()
        {
            return View();
        }

        //
        // POST: /Pa/Create

        [HttpPost]
        public ActionResult Create(iamp_mapping IAMP)
        {
            try
            {
                using (var db = new PaEntities())
                {
                    db.iamp_mapping.Add(IAMP);
                    db.SaveChanges();
                }

                return RedirectToAction("Index");
            }
            catch
            {
                return View();
            }
        }

        //
        // GET: /Pa/Edit/5

        public ActionResult Edit(string id)
        {

            using (var db = new PaEntities())
            {

                return View(db.iamp_mapping.Find(id));
            }
        }

        //
        // POST: /Pa/Edit/5

        [HttpPost]
        public ActionResult Edit(string id, iamp_mapping IAMP)
        {
            try
            {
                using (var db = new PaEntities())
                {
                    db.Entry(IAMP).State = EntityState.Modified;
                    db.SaveChanges();
                    return RedirectToAction("");
                }
            }
            catch
            {
                return View();
            }
        }

        //
        // GET: /Pa/Delete/5

        public ActionResult Delete(string id)
        {
            using (var db = new PaEntities())
            {

                return View(db.iamp_mapping.Find(id));
            }
        }

        //
        // POST: /Pa/Delete/5

        [HttpPost]
        public ActionResult Delete(string id, iamp_mapping IAMP)
        {
            try
            {
                using (var db = new PaEntities())
                {
                    var vIAMP = db.iamp_mapping.Find(id);
                    db.Entry(vIAMP).State = EntityState.Deleted;
                    db.SaveChanges();
                    return RedirectToAction("Index");
                }

            }
            catch (Exception e)
            {
                throw (e);
                //return View();
            }
        }




    }
}

Index.cshtml

@model PagedList.IPagedList<DBFirstMVC.Models.iamp_mapping>

@{
    ViewBag.Title = "Index";
}

@using PagedList;  
<h2>Index</h2>

<p>
    @Html.ActionLink("Create New", "Create")
</p>

@using (Html.BeginForm())
{
    <p>
        Find by PA: @Html.TextBox("SearchString")
        <input type = "submit" value = "Search" />l
    </p>

}
<table>
    <tr>
        <th>
            @Html.ActionLink("PA", "Index", new { sortOrder = ViewBag.NameSortParm })
        </th>
        <th>
            MAJOR PROGRAM
        </th>
        <th>
            INVESTMENT AREA
        </th>
        <th></th>
    </tr>

@foreach (var item in Model) {
    <tr>
        <td>
            @Html.DisplayFor(modelItem => item.PA)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.MAJOR_PROGRAM)
        </td>
        <td>
            @Html.DisplayFor(modelItem => item.INVESTMENT_AREA)
        </td>
        <td>
            @Html.ActionLink("Edit", "Edit", new { id=item.PA }) |

            @Html.ActionLink("Delete", "Delete", new { id=item.PA })
        </td>
    </tr>
}

</table>

<div>
    Page @(Model.PageCount < Model.PageNumber ? 0 : Model.PageNumber)
    of @Model.PageCount

    @if (Model.HasPreviousPage)
    {
        @Html.ActionLink("<<", "Index", new { page = 1, sortOrder = ViewBag.CurrentSort, currentFilter=ViewBag.CurrentFilter  })
        @Html.Raw(" ");
        @Html.ActionLink("< Prev", "Index", new { page = Model.PageNumber - 1, sortOrder = ViewBag.CurrentSort, currentFilter=ViewBag.CurrentFilter  })
    }
    else
    {
        @:<<
        @Html.Raw(" ");
        @:< Prev
    }

    @if (Model.HasNextPage)
    {
        @Html.ActionLink("Next >", "Index", new { page = Model.PageNumber + 1, sortOrder = ViewBag.CurrentSort, currentFilter=ViewBag.CurrentFilter  })
        @Html.Raw(" ");
        @Html.ActionLink(">>", "Index", new { page = Model.PageCount, sortOrder = ViewBag.CurrentSort, currentFilter=ViewBag.CurrentFilter  })
    }
    else
    {
        @:Next >
        @Html.Raw(" ")
        @:>>
    }
</div>

Answer 1

Ok so I figured it out after a ton of googling. The error was completely my fault because after the default case I forgot to add the

IAMP = IAMP.OrderBy(p => p.PA);

all it said before was

IAMP.OrderBy(p => p.PA);

Facepalm = Face + palm

Thanks for everyones help!