MVC Radio Button Lists are not grouped when using the HtmlHelper class

Question

Having trouble creating a list of radio buttons that are grouped together, in MVC 3 specifically, but this also applies to MVC 2.

The problem arises when radio butto

Answer 1

You haven't shown how does your view model look like but you could group them by some property. So let's take an example:

public class MyViewModel
{
    [Required]
    public string SomeProperty { get; set; }
}

Controller:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        return View(new MyViewModel());
    }

    [HttpPost]
    public ActionResult Index(MyViewModel model)
    {
        return View(model);
    }
}

View:

@model AppName.Models.MyViewModel
@using (Html.BeginForm())
{
    <div>A: @Html.RadioButtonFor(x => x.SomeProperty, "a")</div>
    <div>B: @Html.RadioButtonFor(x => x.SomeProperty, "b")</div>
    @Html.ValidationMessageFor(x => x.SomeProperty)
    <input type="submit" value="OK" />
}

Now if you want to preselect some radio simply set the property of the view model to the corresponding value of the radio instead of writing some ugly C# code in your views:

public ActionResult Index()
{
    var model = new MyViewModel
    {
        SomeProperty = "a" // select the first radio
    };
    return View(model);
}

Obviously this technique works with any simple property type (not only strings) and with any number of radio buttons that could be associated to this property.