your model is going to need to contain both the checked values and all the possible values.
public class TestViewModel
{
public Guid Id { get; set; }
public IDictionary<Guid, String> AllCheckboxOptions { get; set; }
public Guid[] CheckedOptions { get; set; }
}
I use Guids as PKs in my database so these are the IDs from the database
I then created a number of extension methods to generate the html
public static MvcHtmlString CheckBoxList(this HtmlHelper htmlHelper, String name, List<SelectListItem> listInfo,
IDictionary<String, Object> htmlAttributes, Int32 columns)
{
if (String.IsNullOrEmpty(name))
throw new ArgumentException("The argument must have a value", "name");
if (listInfo == null)
throw new ArgumentNullException("listInfo");
if (!listInfo.Any())
return new MvcHtmlString(String.Empty);
var outerSb = new StringBuilder();
for (Int32 i = 0; i < columns; i++)
{
var listBuilder = new TagBuilder("ul");
if (columns > 1)
listBuilder.MergeAttribute("class", "column");
var innerSb = new StringBuilder();
var take = listInfo.Count % columns == 0
? listInfo.Count / columns
: (listInfo.Count / columns) + 1;
var items = listInfo.Skip(i * take).Take(take);
foreach (var info in items)
{
var inputBuilder = new TagBuilder("input");
if (info.Selected) inputBuilder.MergeAttribute("checked", "checked");
inputBuilder.MergeAttribute("type", "checkbox");
inputBuilder.MergeAttribute("value", info.Value);
inputBuilder.MergeAttribute("id", info.Value);
inputBuilder.MergeAttribute("name", info.Value);
var labelBuilder = new TagBuilder("label");
labelBuilder.MergeAttribute("for", @info.Value);
labelBuilder.InnerHtml = info.Text;
var listItemWrapper = new TagBuilder("li");
//may have to encode here.
listItemWrapper.InnerHtml = inputBuilder.ToString(TagRenderMode.SelfClosing) + labelBuilder.ToString(TagRenderMode.Normal);
innerSb.Append(listItemWrapper.ToString(TagRenderMode.Normal));
}
listBuilder.InnerHtml = innerSb.ToString();
outerSb.Append(listBuilder.ToString(TagRenderMode.Normal));
}
return new MvcHtmlString(outerSb.ToString());
}
then in the view you can call your extension method
@Html.CheckBoxList("yourtypes", (from o in Model.AllCheckboxOptions
select new SelectListItem
{
Text = o.Value,
Selected = Model.CheckedOptions.Contains(o.Key),
Value = o.Key.ToString()
}).ToList())
I've used this technique with both MVC3 and MVC4 with success.
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