Как решить эту ошибку поискового вызова в asp.net mvc 5?

Question

У меня есть asp.net MVC 5 view. У меня есть следующий код на нем:

@model PagedList.IPagedList<parishV3.Models.HeadsViewModel> 
@using PagedList; 
@using PagedList.Mvc; 
<link href="~/Content/css/PagedList.css" rel="stylesheet" /> 

@using (Html.BeginForm("Index", "Heads", FormMethod.Get)) 
{ 
    <p> 
    <b> Find by name:</b>@Html.RadioButton("findBy", "fname") <text>First Name</text> 
    @Html.RadioButton("findBy", "lname")<text>Last Name</text><br /> 
    @Html.RadioButton("findBy", "h_no")<text>Header Number</text><br /> 
    @Html.TextBox("Seach_Data", ViewBag.FilterValue as string, ViewBag.CurrentFilter as string) 
    <input type="submit" value="Find" /> 
</p> 
} 

<br /> 
Page @(Model.PageCount < Model.PageNumber ? 0 : Model.PageNumber) of @Model.PageCount 
@Html.PagedListPager(Model, page => Url.Action("Index", new { page, findby = Request.QueryString["findby"], Seach_Data = Request.QueryString["Seach_Data"] })) 

контроллер

public ActionResult Index(string Seach_Data, string findby, int? page, string currentFilter) 
{ 
    if (findby == "fname") 
    { 
     string query = "SELECT v.h_no as h_no, v.h_initials , v.h_id as h_id , t.titles as titles,  p.Suburb as Suburb, p.flatNo as flatNo, p.flatName as flatName,v.Email as Email, v.cell as cell, v.tel_h as tel_h, v.fname as fname, p.strname as strname, p.strNo as strNo, p.City as City, LEFT(v.lname, 255) as lname from [dbo].[Heads] v, [dbo].[Addresses1] p, [dbo].[Titles] t WHERE v.[h_ID] = p.[h_id] and v.[title_id]= t.[title_id] "; 

     var ViewModel = db.Database.SqlQuery<HeadsViewModel>(query); 
     return View(ViewModel.Where(x => x.fname == Seach_Data).ToList().ToPagedList(page ?? 1, 4)); 
    } 
    else if (findby == "lname") 
    { 
     string query = "SELECT v.h_no as h_no, v.h_initials , v.h_id as h_id , t.titles as titles, p.Suburb as Suburb, p.flatNo as flatNo, p.flatName as flatName,v.Email as Email, v.cell as cell, v.tel_h as tel_h, v.fname as fname, p.strname as strname, p.strNo as strNo, p.City as City, LEFT(v.lname, 255) as lname from [dbo].[Heads] v, [dbo].[Addresses1] p, [dbo].[Titles] t WHERE v.[h_ID] = p.[h_id] and v.[title_id]= t.[title_id] "; 
     var ViewModel = db.Database.SqlQuery<HeadsViewModel>(query); 

     return View(ViewModel.Where(x => x.lname == Seach_Data).ToList().ToPagedList(page ?? 1, 6)); 
    } 
    else 
    { 
     string query = "SELECT v.h_no as h_no, v.h_initials , v.h_id as h_id , t.titles as titles, p.Suburb as Suburb, p.flatNo as flatNo, p.flatName as flatName,v.Email as Email, v.cell as cell, v.tel_h as tel_h, v.fname as fname, p.strname as strname, p.strNo as strNo, p.City as City, LEFT(v.lname, 255) as lname from [dbo].[Heads] v, [dbo].[Addresses1] p, [dbo].[Titles] t WHERE v.[h_ID] = p.[h_id] and v.[title_id]= t.[title_id] "; 
     var ViewModel = db.Database.SqlQuery<HeadsViewModel>(query); 
     return View(ViewModel); 
    } 
} 

Моя проблема заключается в том, что при запуске проекта он дает мне ошибку, которая говорит:

системы. InvalidOperationException: элемент модели, переданный в словарь, имеет тип System.Data.Entity.Infrastructure.DbRawSqlQuery 1[parishV3.Models.HeadsViewModel], but this dictionary requires a model item of type 'PagedList.IPagedList 1 [parishV3.Models .HeadsViewModel].»

Answer 1

В начальной загрузке страницы значение findby равно нулю, поэтому else блок выполняется, который возвращает DbRawSqlQuery1<parishV3.Models.HeadsViewModel>, но ваш взгляд требует модель быть IPagedList1<parishV3.Models.HeadsViewModel>. Изменение вам else блока

else 
{ 
    string query = "....."; 
    var ViewModel = db.Database.SqlQuery<HeadsViewModel>(query); 
    return View(ViewModel.ToList().ToPagedList(1, 6)); 
} 

Примечания при использовании страничного списка, запрос должны включать в себя OrderBy положения, чтобы обеспечить сбор всегда возвращаются в том же порядке, в противном случае вы можете получить непредсказуемые результаты.