Question

I’m not so experienced using MVC. I’m dealing with this situation. Everything works well until call the HttpPost method where has all its members null. I don’t know why is not persisting all the data on it.

And everything works well, because I can see the data in my Html page, only when the user submit the information is when happens this.

    [HttpGet]
    public ActionResult DoTest()
    {
        Worksheet w = new Worksheet(..);
        return View(w);
    }

    [HttpPost]
    public ActionResult DoTest(Worksheet worksheet)
    {
        return PartialView("_Problems", worksheet);
    }

This is class which I’m using.

public class Worksheet
{
    public Worksheet() { }

    public Worksheet(string title, List<Problem> problems)
    {
        this.Title = title;
        this.Problems = problems;
    }

    public Worksheet(IEnumerable<Problem> problems, WorksheetMetadata metadata, ProblemRepositoryHistory history)
    {
        this.Metadata = metadata;
        this.Problems = problems.ToList();
        this.History = history;
    }

    public string Title { get; set; }
    public List<Problem> Problems { get; set; }  // Problem is an abstract class
    public WorksheetMetadata Metadata { get; set; }
    public ProblemRepositoryHistory History { get; set; }
}

And my razor view…. the razor view shows successfully my view. I realized something rare, please note in my 5 and 6 lines that I have HiddenFor method, well if I used that, when calls HTTPPOST persists the data, I don’t know why.

@model Contoso.ExercisesLibrary.Core.Worksheet

<div id="problemList">
<h2>@Html.DisplayFor(model => model.Metadata.ExerciseName)</h2>
    @Html.HiddenFor(model => model.Metadata.ExerciseName)
    @Html.HiddenFor(model => model.Metadata.ObjectiveFullName)

@for (int i = 0; i < Model.Problems.Count; i++)
{
    <div>
    @Html.Partial(Contoso.ExercisesLibrary.ExerciseMap.GetProblemView(Model.Problems[i]), Model.Problems[i])
    </div>
}
</div>

UPDATE
I’m using a static class to get the view name, but as I’m testing I’m just using this Partial view

@model Contoso.ExercisesLibrary.AbsoluteArithmetic.Problem1
<div>

    <span style="padding:3px; font-size:18px;">@Model.Number1</span>
    <span style="padding:5px; font-size:18px;">+</span>
    <span style="padding:5px; font-size:18px;">@Model.Number2</span>
    <span style="padding:5px; font-size:18px;">=</span>

    <span style="font-size:18px">
            @Html.EditorFor(model => model.Result, new { style = "width:60px; font-size:18px;" })
            @Html.ValidationMessageFor(model => model.Result)
    </span>
</div>

@section Scripts {

}

And here the user do the post

@model Contoso.ExercisesLibrary.Core.Worksheet

<form method="post">
    @Html.Partial("_Problems", Model)

    <input type="submit" value="Continue" />
</form>

Answer 1

The Model Binder will ‘bind’ or link input fields on your view to the model. It will not bind display fields (like label), that is why you need the HiddenFor it will add an <input type="hidden" which will then be bound to the Model when you Post.