如何在ASP.NET MVC中创建CheckBoxListFor扩展方法？

请随时改进这个和转发:-)

//View

<%: Html.CheckBoxListFor(model => model.FreightTypeIds,FreightTypeMultiSelectList)  %>

//Controller

    public ActionResult SomeAction(int[] FreightTypeIds)
    {
       //...

       return View();
    }


//Extension
public static MvcHtmlString CheckBoxListFor<TModel,TProperty>(this HtmlHelper<TModel> htmlHelper,Expression<Func<TModel,IEnumerable<TProperty>>> expression,MultiSelectList allOptions,object htmlAttributes = null)
{
    ModelMetadata modelMetadata = ModelMetadata.FromLambdaExpression<TModel,IEnumerable<TProperty>>(expression,htmlHelper.ViewData);

    // Derive property name for checkbox name
    string propertyName = htmlHelper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(modelMetadata.PropertyName);

    // Get currently select values from the ViewData model
    IEnumerable<TProperty> list = expression.Compile().Invoke(htmlHelper.ViewData.Model);

    // Convert selected value list to a List<string> for easy manipulation
    IList<string> selectedValues = new List<string>();

    if (list != null)
    {
        selectedValues = new List<TProperty>(list).ConvertAll<string>(delegate(TProperty i) { return i.ToString(); });
    }

    // Create div
    TagBuilder divTag = new TagBuilder("div");
    divTag.MergeAttributes(new RouteValueDictionary(htmlAttributes),true);

    // Add checkboxes
    foreach (SelectListItem item in allOptions)
    {
        divTag.InnerHtml += string.Format(
                                          "<div><input type="checkbox" name="{0}" id="{1}_{2}" " +
                                          "value="{2}" {3} /><label for="{1}_{2}">{4}</label></div>",propertyName,TagBuilder.CreateSanitizedId(propertyName),item.Value,selectedValues.Contains(item.Value) ? "checked="checked"" : string.Empty,item.Text);
    }

     return MvcHtmlString.Create(divTag.ToString());
}