Question

I am developing a web survey application in ASP.Net Mvc3. I use PagedList in my application to paginate the questions page alone.

I get the following error:

The model item passed into the dictionary is of type
'PagedList.PagedList`1[SWSSMVC.Models.ViewModels.QuestionViewModel]', 
but this dictionary requires a model item of type 
'PagedList.IPagedList`1[SWSSMVC.Models.ViewModels.QuestionListViewModel]'.

There is a question which is of similar nature. The solution says not to specify anonymous type, as far as I understood. Can someone point out where in my code I have anonymous type? I believe I have typed all my variables with appropriate models.

This is the question Controller:

public class QuestionController : SessionController
{
    DBManager dbmgr = new DBManager();

    //
    // GET: /Question/

    public ActionResult Index(string currentSection, string currentPage, int? page)
    {
        int j;

        SectionSession = currentSection;
        PageSession = currentPage;

        var questionList = new QuestionListViewModel();

        int questionCount = dbmgr.getQuestionCount(currentPage);
        var question = new QuestionViewModel();
        for(int i=1 ; i<=questionCount; i++)
        {
            int questionid = dbmgr.getQuestionid(currentPage, i);
            string questiontext = dbmgr.getQuestion(questionid);

            List<string> oldchoices = dbmgr.getChoicesAns(questionid);
            ChoiceViewModel choice = new ChoiceViewModel();
            question = new QuestionViewModel { QuestionId = questionid, QuestionText = questiontext, Answer = oldchoices.Last()};

            for (j = 0; j < oldchoices.Count() - 1; j++)
            {
                if (oldchoices[j] != null)
                {
                    question.Choices.Add(new ChoiceViewModel { ChoiceId = j, ChoiceText = oldchoices[j] });
                }
            }
            questionList.Questions.Add(question);
        }

        int pageSize = 3;
        int pageNumber = (page ?? 1);

        return View(questionList.Questions.ToPagedList(pageNumber, pageSize));
    }

There are two models:

public class QuestionViewModel
{
    public int QuestionId { get; set; }
    public string QuestionText { get; set; }
    public List<ChoiceViewModel> Choices { get; set; }
    public string Answer { get; set; }
    [Required]
    public string SelectedAnswer { get; set; }
    public QuestionViewModel()
    {
        Choices = new List<ChoiceViewModel>();
    }
}

public class QuestionListViewModel
{
    public List<QuestionViewModel> Questions { set; get; }
    public QuestionListViewModel()
    {
        Questions = new List<QuestionViewModel>();
    }
}

I am entering my part- Index View code for the above Question Controller

@model PagedList.IPagedList<SWSSMVC.Models.ViewModels.QuestionListViewModel>
@{
    ViewBag.Title = "Index";
 }

 <h2>Questions</h2>

 @using (Html.BeginForm())
 {
    @Html.ValidationSummary(true)
    <fieldset>
       @foreach (var item in Model)
       {
           @Html.EditorFor(x => item.Questions)
       }

I also have a Editor Template like this

@model SWSSMVC.Models.ViewModels.QuestionViewModel
<div>
@Html.HiddenFor(x => x.QuestionId)
<h3> @Model.QuestionText </h3>
@foreach (var a in Model.Choices)
{
   <p>
      @Html.RadioButtonFor(b => b.SelectedAnswer, a.ChoiceText)  @a.ChoiceText 
   </p>
}
</div>

I tried to run through the code a couple of times and having hard time figuring it out. I also do not know how I could have made the questionList as a LINQ variable, given that, my questionList is inturn constructed with questions and choices from a separate model.

Answer 1

Creator of PagedList here. The problem is that this line:

return View(questionList.Questions.ToPagedList(pageNumber, pageSize));

Is sending a model of type IPagedList down to the page (because the extension method is being applied to a type of List), but your page says it is expecting:

@model PagedList.IPagedList<SWSSMVC.Models.ViewModels.QuestionListViewModel>

Changing your view code to say this instead should fix it:

@model PagedList.IPagedList<SWSSMVC.Models.ViewModels.QuestionViewModel>