how to process strongly typed MVC3 view where model has nested collections?

Question

i have a model that has a Collections of "Questions". Each Question has a collection of "PossibleAnswers". The possible answer objects have an isAnswer property which should be bound to the selected radio button (in the group for each question) that represents the question.

I am new to MVC and really not sure how to build the view so that the posted model will have the collection of possibleanswers for each question with one of the objects having the isAnswer property set as true, based on the selection from the associated radio button group.

Right now the view should build a radio button group/list for each question with the possibleanswer collection of the question representing a radio button choice related to the question. Can i do nested loop in razor? do you use partials? how does MVC know how to rebuild the model based on the view when i post it??

score 1 · Answer 1 · answered Jun 22 '11 at 01:46

It's actually very simple. The tricky part is to use indexers

    namespace MvcApplication2.Controllers
{
    public class QuizModel
    {
        public IList<QuestionModel> Questions { get; set; }
    }
    public class QuestionModel
    {
        public IList<AnswerModel> PossibleAnswers { get; set; }       
    }
    public class AnswerModel
    {
        public bool IsAnswer { get; set; }
    }


    public class HomeController : Controller
    {
        //
        // GET: /Home/

        public ActionResult Index()
        {
            return View(new QuizModel
                            {
                                Questions = Enumerable.Repeat(
                                    new QuestionModel
                                        {
                                            PossibleAnswers = Enumerable.Repeat(new AnswerModel(), 3).ToList()
                                        }, 2).ToList()
                            });
        }
        [HttpPost]
        public ActionResult Index(QuizModel model)
        {
            return View(model);
        }
    }}

Then your view

@model MvcApplication2.Controllers.QuizModel
@{
    View.Title = "Index";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>
    Index</h2>
    @using (Html.BeginForm())
    {
for (int i = 0; i < Model.Questions.Count; i++)
{
    for (int j = 0; j < Model.Questions[i].PossibleAnswers.Count; j++)
    {
    <div>
        @Html.EditorFor(c => Model.Questions[i].PossibleAnswers[j].IsAnswer)
    </div>
    }
}
<input type="submit" value="Submit" />
    }

how to process strongly typed MVC3 view where model has nested collections?

1 Answers1