模型在发布时为空

Question

When I submit, my model is empty on post.

Model

public QuizModel()
{
    Questions = new List<QuizQuestionModel>();
}

public QuizModel(string quizName)
{
    QuizName = quizName;
    Score = 0;
    IntranetEntities db = new IntranetEntities();
    Quiz quiz = db.Quizs.Where(x => x.Name.Equals(quizName, StringComparison.InvariantCultureIgnoreCase)).FirstOrDefault();
    if (quiz != null)
    {
        IQueryable<Quiz_Question> questions = db.Quiz_Question.Where(x => x.QuizID.Equals(quiz.ID)).OrderBy(x => x.QuestionNo);

        Questions = new List<QuizQuestionModel>();
        foreach (Quiz_Question question in questions)
        {
            QuizQuestionModel q = new QuizQuestionModel();
            q.ID = question.ID;
            q.Question = question.Question;
            q.UserAnswer = null;
            q.SystemAnswer = question.Answer;
            Questions.Add(q);
        }
    }
}

public string QuizName { get; set; }
public List<QuizQuestionModel> Questions { get; set; }
public int Score { get; set; }

Controller

[HttpPost]
public ActionResult OSHAQuiz(Models.QuizModel model)
{
    if (ModelState.IsValid)
    {
        bool passed = false;

        model.Score = model.Questions.Where(x => x.UserAnswer.Equals(x.SystemAnswer, StringComparison.InvariantCultureIgnoreCase)).Count();

        if (!model.Score.Equals(0))
        {
            double percent = model.Score / model.Questions.Count();

            if (percent >= .8)
            {
                passed = true;
            }
        }

        if (passed)
        {
            return View("/Views/Quiz/Passed.cshtml");
        }
        else
        {
            return View("/Views/Quiz/Failed.cshtml");
        }
    }
    else
    {
        return View("/Views/Quiz/Quiz.cshtml", model);
    }
}

View

@model PAL.Intranet.Models.QuizModel

<script>
    $(document).ready(function () {
        $("input:checked").removeAttr("checked");
    });
</script>

<div class="grid">

    <h2>OSHA Quiz</h2>
    <hr />

    <div class="align-center">

        @using (Html.BeginForm("OSHAQuiz", "Quiz", FormMethod.Post, new { id = "formShowLoading" }))
        {
            @Html.AntiForgeryToken()
            @Html.ValidationSummary(true)
            <div class="row cell">
                <div class="example bg-grayLighter" data-text="Directions">
                    <ul class="simple-list">
                        <li class="align-left">When you have made your selection for all 20 statements, click on the button 'Submit.'</li>
                        <li class="align-left">Mark 'True' or 'False' for each statement.</li>
                        <li class="align-left">You must score 80% (16 correct) to pass.</li>
                        <li class="align-left">You must fill in your full name to receive credit.</li>
                    </ul>
                </div>
            </div>

            <div class="row cell">
                <div class="row cell">
                    <div class="panel" data-role="panel">
                        <div class="heading">
                            <span class="title">Questions</span>
                        </div>
                        <div class="content">
                            <ul class="numeric-list">
                                @foreach (var question in Model.Questions)
                                {
                                    <li>
                                        <table class="table hovered" style="width: 100%;">
                                            <tr>
                                                <td align="left">@question</td>
                                                <td align="right" width="150px">
                                                    <div class="align-center">
                                                        <label class="align-right input-control radio small-check">
                                                            @Html.RadioButtonFor(model => question.UserAnswer, true, new { Name = question.GroupName })
                                                            <span class="check"></span>
                                                            <span class="caption">True</span>
                                                        </label>

                                                        <label class="align-right input-control radio small-check">
                                                            @Html.RadioButtonFor(model => question.UserAnswer, false, new { Name = question.GroupName })
                                                            <span class="check"></span>
                                                            <span class="caption">False</span>
                                                        </label>
                                                    </div>
                                                </td>
                                            </tr>
                                        </table>
                                    </li>
                                }
                            </ul>
                        </div>
                    </div>
                </div>
            </div>

            <div class="row cell">
                <input type="submit" value="Submit" class="button info small-button" />
                <input type="reset" value="Reset" class="button primary small-button" />
            </div>
        }
    </div>
</div>

UPDATE

if I use HiddenFor on QuizName, it does come back over on post but the rest of the model is empty.

Answer 1

When iterating over a collection that you want to post back to your model, you can't use foreach ; you must use a regular for statement with indexing in order for Razor to generate the correct field names.

@for (var i = 0; i < Model.Questions.Count(); i++)
{
    ...
    @Html.RadioButtonFor(m => m.Questions[i].UserAnswer)
}

Then, your fields will have name attributes in the form of Questions[0].UserAnswer , which the modelbinder will recognize and bind appropriately to your model. As you have it now, with the foreach , the field name is being generated as question.UserAnswer , which the modelbinder has no idea what to do with and discards.

Also, FWIW, accessing your context from within your model entity is a hugely bad idea, and even worse if you're not injecting it. Move that logic out of your entity and utilize a utility class or service instead. Also, look into dependency injection, as your context is one of those things that you want one and only one instance of per request. If you start instantiating multiple instances of the same context, you will have problems.

Answer 2

The problem is model binding is going to attempt to bind your form values to properties on your model. It will not use the constructor on your model that takes the quiz name, it will use the default constructor to instantiate the QuizModel object.

I would consider refactoring this model to remove your EntityFramework dependency and find a new way to populate those values.

You should also call the Dispose() method on IDisposable objects when you're done using them.

My suggestion for how to solve this problem would be to use the QuizModel you currently have to help render your view (ie Your quiz questions and possible answer for each question).

Create a seperate ViewModel for quiz submission

public class QuizSubmission
{
  public string QuizName { get;set; }

  public List<QuizQuestionResponse> Responses { get;set; }
}

public class QuizQuestionResponse
{
   public int QuestionId { get;set; }
   public int AnswerId { get;set; }
}

In your controller action, you should be binding to a QuizSubmission model.

[HttpPost]
public ActionResult OSHAQuiz(Models.QuizSubmission model)
{

Then you'll be able to perform any actions you need for that quiz submission (ie. data access, validation ).

You'll also need to update your view so that your Html input elements have the correct name attributes that model binding can correctly bind each question and response pair to a QuizQuestionResponse item in your Responses list.