MVC, CheckboxList extension html helper..further issues - asp.net-mvc

Question

Good afternoon
I'm hoping this is going to be nice and a simple f**k up by myself but I've gone in deep and currently can't swim.
Ok, previously I asked this question and as such I have implemented the following:
Model
public class CorporateDetails
{
public Guid? Id { get; set; }
[Key]
public int CorporateDetailId { get; set; }
public int? EmsId { get; set; }
public string EmsName { get; set; }
public virtual EmsType EmsType { get; set; }
}
public class EmsType
{
[Key]
public int? EmsId { get; set; }
public string EmsName { get; set; }
public virtual ICollection<EmsType> EmsTypes { get; set; }
}
Controller
public ActionResult Create()
{
ViewBag.EmsId = new MultiSelectList(db.EmsTypes, "EmsId", "EmsName");
return View();
}
View
<fieldset>
<legend>CorporateDetails</legend>
<div class="editor-label">
#Html.LabelFor(model => model.EmsId, "EmsType")
</div>
<div class="editor-field">
#Html.DropDownList("EmsId", String.Empty)
#Html.ValidationMessageFor(model => model.EmsId)
</div>
<div class="editor-label">
#Html.CheckBoxListFor(model => model.EmsId, (MultiSelectList) ViewBag.EmsId)
</div>
<p>
<input type="submit" value="Create" />
</p>
</fieldset>
}
<div>
#Html.ActionLink("Back to List", "Index")
</div>
#section Scripts {
#Scripts.Render("~/bundles/jqueryval")
}
Where this CheckBoxListFor uses the following extension:
public static class HtmlHelper
{
//Extension
public static MvcHtmlString CheckBoxListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty[]>> expression, MultiSelectList multiSelectList, object htmlAttributes = null)
{
//Derive property name for checkbox name
MemberExpression body = expression.Body as MemberExpression;
string propertyName = body.Member.Name;
//Get currently select values from the ViewData model
TProperty[] list = expression.Compile().Invoke(htmlHelper.ViewData.Model);
//Convert selected value list to a List<string> for easy manipulation
List<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 multiSelectList)
{
divTag.InnerHtml += String.Format("<div><input type=\"checkbox\" name=\"{0}\" id=\"{0}_{1}\" " +
"value=\"{1}\" {2} /><label for=\"{0}_{1}\">{3}</label></div>",
propertyName,
item.Value,
selectedValues.Contains(item.Value) ? "checked=\"checked\"" : "",
item.Text);
}
return MvcHtmlString.Create(divTag.ToString());
}
}
So what's the problem?
Well when I run it I get a nasty error telling me:
"CS0411: The type arguments for method
'Extensions.HtmlHelper.CheckBoxListFor(System.Web.Mvc.HtmlHelper,
System.Linq.Expressions.Expression>,
System.Web.Mvc.MultiSelectList, object)' cannot be inferred from the
usage. Try specifying the type arguments explicitly."
Can someone please point out where I have gone wrong as I'm going round in circles and not sure what I have missed.
Any help gratefully appreciated.

Answer 1

Ricardo,
I have shared some of my own MVC helpers on GitHub. Please feel free to browse & use the code as needed. One of the items in the project is a CheckBoxListItemFor helper, it was created specifically to create checkbox lists. Look under InputExtensions.cs
https://github.com/EdCharbeneau/EJC.UIExtensions/tree/master/EJC.UIExtensions/Html

Answer 2

The problem with this here is that my original EmsId is a nullable int and not an int array as required and hence the error.
Please refer to my answer given here for a full explanation of how this can be achieved.