未从View传递到Controller的ModelView数据

Question

My problem is that strongly typed data passed from my Controller to my view comes out empty (all it's properties are null).

I would also like to bind selected value in radiobuttons (marked as QUESTION2) to model property "GivenAnwser" but it doesn't seem to work either.

Type passed around is a ViewModel

public class HomeController : Controller
    {
        [HttpGet]
        public ActionResult Index()
        {  
            QuestionViewModel question = Manager.GetQuestion();
            return View(question);
        }

        [HttpPost]
        public ActionResult Index(QuestionViewModel question,Anwser givenAnwser)
        {      
            //QuestionViewModel  is returned but all it's properties are null.           
            return View(question);
        }
    }

VIEW

@model Quiz.ViewModels.QuestionViewModel
@{
    ViewBag.Title = "Home Page";
}

@Html.Label("Question:")

@if (Model.CorrectAnwser != null)
{
    //some code
}

@Html.DisplayFor(model => model.Question.Text)

//I have tried with Hidden fields and without them
@Html.HiddenFor(model => model.Question)
@Html.HiddenFor(model => model.Anwsers)
@using (Html.BeginForm("Index", "Home"))
{         
    foreach (var anwser in Model.Anwsers)
    {
        //QUESTION 2
        <input type="radio" name="givenAnwser" value="@anwser" />
        <label>@anwser.Text</label>
        <br />
    }
    <input type="submit" value="Check!" />
}

QuestionViewModel

public class QuestionViewModel
    {
        public QuestionViewModel()
        {
            this.Anwsers = new List<Anwser>();
        }

        public Question Question { get; set; }

        public List<Anwser> Anwsers { get; set; }

        public Anwser GivenAnwser { get; set; }

        public bool CorrectAnwser { get; set; }

    }

EDIT: ModelState contains an error:
"The parameter conversion from type 'System.String' to type 'Quiz.Models.Anwser' failed because no type converter can convert between these types."

Answer 1

 <input type="radio" name="givenAnwser" value="@anwser" />

this line is setting a complex type "@answer" as the value of the radio button. this might just do a ToString() of the type during rendering.

When you post it back, MVC might be trying to convert this string value back to

Quiz.Models.Anwser

and failing.

you should probably render

<input type="radio" name="givenAnwser" value="@anwser.SomeBooleanValue" />

ps also, why not use the Html Extension to render the radio button.

Answer 2

You can't bind a complex type (Question) to a Hidden field. You would need to bind to the separate child properties.

Also, for the answers, don't use a foreach, use a for loop. Like:

@for(var i=0;i<Answers.Count;i++)
{
    <input type="radio" name="@Html.NameFor(a=>a.Answers[i].answer.Value)" value="@Model.Answers[i].anwser.Value" />
}

or

@for(var i=0;i<Answers.Count;i++)
{
    @Html.RadioButtonFor(a=>a.Answers[i].answer,Model.Answers[i].answer.Value)
}

Although, that may not be correct either because Answers is a collection of a complex type as well, and you didn't share it's definition.

All in all, I don't think you really need (or want) to post back the entire Model back anyhow. Why not just post back the question ID, and the selected Answer?