C# – Asp.net MVC Razor how to show grouped radio buttons for two model fields

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I have a simple quiz model, and I am trying to let the user select Correct Answer/Alternative answer from two radio buttons, grouped , in a strongly typed view. But the lambda expressions I use aren't working. I get two blank radio buttons. I have looked at several questions here, and online but my model is an IList<>, and I can't find a suitable example. All examples I found work with a non-IList<>.

This is my Model

Model:

public partial class Question
    {
        public int QuestionID { get; set; }
        public string QuestionBody { get; set; }
        public string CorrectAnswer { get; set; }
        public string AlternativeAnswer { get; set; }           
    }

My Controller

public ActionResult Index()
        {
            QuizSimpleEntities quizEntities = new QuizSimpleEntities();
            var questions = from p in quizEntities.Questions
                            select p;

            return View(questions.ToList());

        }

My Model:

  @model IList<Quiz.Models.Question>                                

 <h2>Welcome to the Quiz</h2>
  @Html.BeginForm(method:FormMethod.Post,controllerName:"Home",actionName:"index")
    {
        @foreach (var questions in Model)
        {

        <p>@questions.QuestionBody</p>  

        @* How to display the CorrectAnswer and AlternativeAnswer
           as two radio buttons grouped here? I will be posting the selected value back
        }

}

Thank you

Best Answer

You need to have a property on your view model that will hold the selected answer when the form is posted:

public partial class Question
{
    public int QuestionID { get; set; }
    public string QuestionBody { get; set; }
    public string CorrectAnswer { get; set; }
    public string AlternativeAnswer { get; set; }           

    public string SelectedAnswer { get; set; }
}

and then simply loop through the elements of your model and generated the desired markup:

@model IList<Quiz.Models.Question>                                

<h2>Welcome to the Quiz</h2>
@Html.BeginForm( method:FormMethod.Post, controllerName:"Home", actionName:"index")
{
    @for (var i = 0; i < Model.Count; i++)
    {
        @Html.HiddenFor(x => x[i].QuestionID)
        <fieldset>
            <legend>
                @Html.DisplayFor(x => x[i].QuestionBody)
            </legend>
            <ul>
                <li>
                    @Html.HiddenFor(x => x[i].CorrectAnswer)
                    @Html.RadioButtonFor(x => x[i].SelectedAnswer, Model[i].CorrectAnswer)
                    @Html.DisplayFor(x => x[i].CorrectAnswer)
                </li>
                <li>
                    @Html.HiddenFor(x => x[i].AlternativeAnswer)
                    @Html.RadioButtonFor(x => x[i].SelectedAnswer, Model[i].AlternativeAnswer)
                    @Html.DisplayFor(x => x[i].AlternativeAnswer)
                </li>
            </ul>
        </fieldset>
    }

    <button type="submit">OK</button>
}

NOTE: When the form is submitted the POST action could take an IList<Question> model where you will have the answers for each question (in the SelectedAnswer property).

For MVC v5.1 use Html.EnumDropDownListFor

@Html.EnumDropDownListFor(
    x => x.YourEnumField,
    "Select My Type", 
    new { @class = "form-control" })

For MVC v5 use EnumHelper

@Html.DropDownList("MyType", 
   EnumHelper.GetSelectList(typeof(MyType)) , 
   "Select My Type", 
   new { @class = "form-control" })

For MVC 5 and lower

I rolled Rune's answer into an extension method:

namespace MyApp.Common
{
    public static class MyExtensions{
        public static SelectList ToSelectList<TEnum>(this TEnum enumObj)
            where TEnum : struct, IComparable, IFormattable, IConvertible
        {
            var values = from TEnum e in Enum.GetValues(typeof(TEnum))
                select new { Id = e, Name = e.ToString() };
            return new SelectList(values, "Id", "Name", enumObj);
        }
    }
}

This allows you to write:

ViewData["taskStatus"] = task.Status.ToSelectList();

by using MyApp.Common

C# – How to handle multiple submit buttons in ASP.NET MVC Framework

Here is a mostly clean attribute-based solution to the multiple submit button issue based heavily on the post and comments from Maarten Balliauw.

[AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
public class MultipleButtonAttribute : ActionNameSelectorAttribute
{
    public string Name { get; set; }
    public string Argument { get; set; }

    public override bool IsValidName(ControllerContext controllerContext, string actionName, MethodInfo methodInfo)
    {
        var isValidName = false;
        var keyValue = string.Format("{0}:{1}", Name, Argument);
        var value = controllerContext.Controller.ValueProvider.GetValue(keyValue);

        if (value != null)
        {
            controllerContext.Controller.ControllerContext.RouteData.Values[Name] = Argument;
            isValidName = true;
        }

        return isValidName;
    }
}

razor:

<form action="" method="post">
 <input type="submit" value="Save" name="action:Save" />
 <input type="submit" value="Cancel" name="action:Cancel" />
</form>

and controller:

[HttpPost]
[MultipleButton(Name = "action", Argument = "Save")]
public ActionResult Save(MessageModel mm) { ... }

[HttpPost]
[MultipleButton(Name = "action", Argument = "Cancel")]
public ActionResult Cancel(MessageModel mm) { ... }

Update: Razor pages looks to provide the same functionality out of the box. For new development, it may be preferable.

Best Answer

Related Solutions

C# – How to create a dropdownlist from an enum in ASP.NET MVC

For MVC v5.1 use Html.EnumDropDownListFor

For MVC v5 use EnumHelper

For MVC 5 and lower

C# – How to handle multiple submit buttons in ASP.NET MVC Framework

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