Asp.net-mvc – Html.DropDownList size attribute

Html.CheckBox is doing something weird - if you view source on the resulting page, you'll see there's an <input type="hidden" /> being generated alongside each checkbox, which explains the "true false" values you're seeing for each form element.

Try this, which definitely works on ASP.NET MVC Beta because I've just tried it.

Put this in the view instead of using Html.CheckBox():

<% using (Html.BeginForm("ShowData", "Home")) {  %>
  <% foreach (var o in ViewData.Model) { %>
    <input type="checkbox" name="selectedObjects" value="<%=o.Id%>">
    <%= o.Name %>
  <%}%>
  <input type="submit" value="Submit" />
<%}%>

Your checkboxes are all called selectedObjects, and the value of each checkbox is the GUID of the corresponding object.

Then post to the following controller action (or something similar that does something useful instead of Response.Write())

public ActionResult ShowData(Guid[] selectedObjects) {
    foreach (Guid guid in selectedObjects) {
        Response.Write(guid.ToString());
    }
    Response.End();
    return (new EmptyResult());
}

This example will just write the GUIDs of the boxes you checked; ASP.NET MVC maps the GUID values of the selected checkboxes into the Guid[] selectedObjects parameter for you, and even parses the strings from the Request.Form collection into instantied GUID objects, which I think is rather nice.

The key here is to add

 <add namespace="System.Web.Optimization" /> 

to BOTH web.config files. My scenario was that I had System.Web.Optimization reference in both project and the main/root web.config but @Scripts still didn't work properly. You need to add the namespace reference to the Views web.config file to make it work.

UPDATE:

Since the release of MVC 4 System.Web.Optimization is now obsolete. If you're starting with a blank solution you will need to install the following nuget package:

Install-Package Microsoft.AspNet.Web.Optimization

You will still need to reference System.Web.Optimization in your web.config files. For more information see this topic:

How to add reference to System.Web.Optimization for MVC-3-converted-to-4 app

As many pointed out, restart of VS could be required after the above steps to make this work.