Grouping Radio Buttons in ASP.NET MVC 5

Question:

In an ASP.NET MVC 5 application, a form has multiple sets of radio buttons. Each group represents a question, but the code snippet only generates one group, causing only the first question to have selected radio buttons while deselecting others. How can this be resolved to group radio buttons correctly by question?

Answer:

To group radio buttons by question, several issues in the provided code need to be addressed:

• Duplicate ids: Ensure unique ids for radio buttons to prevent invalid HTML.
• Duplicate name attributes: Avoid duplicate name attributes to create multiple groups. Instead, group radio buttons by assigning them the same name attribute.
• Binding to an incorrect property: Properly bind radio buttons to their associated question property.

Modified Code:

@foreach (var question in Model.GeneralQuestions)
{
    <div class="well">
        <h3><strong>@question.QuestionString</strong></h3>
        @foreach (var answer in question.PossibleAnswers)
        {
            @Html.RadioButtonFor(
                model => model.GeneralQuestions.IndexOf(question), // Binding to index of question in list
                answer.Answer,
                new { id = $"question_{question.QuestionID}_answer_{answer.Answer}" })
            @Html.Label(answer.Answer)
            <br />
        }
    </div>
}

View Models:

Create view models with properties to bind to the radio buttons and display questions.

public class QuestionVM
{
    public string QuestionString { get; set; }
    public IEnumerable<AnswerVM> PossibleAnswers { get; set; }
}

public class StudentVM
{
    public int ID { get; set; }
    public string Name { get; set; }
    public List<SubjectVM> Subjects { get; set; }
}

public class SubjectVM
{
    public string Name { get; set; }
    public List<QuestionVM> Questions { get; set; }
}

View:

@model StudentVM
@using (Html.BeginForm())
{
    @Html.HiddenFor(m => m.ID)
    @Html.DisplayFor(m => m.Name)
    for (int i = 0; i < Model.Subjects.Count; i++)
    {
        @Html.HiddenFor(m => m.Subjects[i].ID)
        @Html.DisplayFor(m => m.Subjects[i].Name)
        for (int j = 0; j < Model.Subjects[i].Questions.Count; j++)
        {
            @Html.HiddenFor(m => m.Subjects[i].Questions[j].ID)
            @Html.DisplayFor(m => m.Subjects[i].Questions[j].QuestionString)
            foreach (var answer in Model.Subjects[i].Questions[j].PossibleAnswers)
            {
                <div>
                    @Html.RadioButtonFor(
                        m => m.Subjects[i].Questions[j].SelectedAnswer,
                        answer.ID,
                        new { id = $"question_{SubjectQuestions[i].Questions[j].ID}_answer_{answer.ID}" })
                    <label for="@answer.ID">@answer.Text</label>
                </div>
            }
        }
    }
    <input type="submit" value="save" />
}

Controller:

public ActionResult Edit(int ID)
{
    StudentVM model = new StudentVM();
    // Populate model with data from database
    return View(model);
}

[HttpPost]
public ActionResult Edit(StudentVM model)
{
    // Save and redirect
    return RedirectToAction("Index");
}

This modified code:

• Binds radio buttons to the correct property (the index of the question in the list).
• Creates unique ids for radio buttons and uses consistent naming conventions.
• Uses view models for better organization and data representation.

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