How to use dashes in HTML-5 data-* attributes in ASP.NET MVC

Question

I am trying to use HTML5 data- attributes in my ASP.NET MVC 1 project. (I am a C# and ASP.NET MVC newbie.)

 <%= Html.ActionLink("« Previous", "Search",      new { keyword = Model.Keyword, page = Model.currPage - 1},      new { @class = "prev", data-details = "Some Details"   })%> 

The "data-details" in the above htmlAttributes give the following error:

 CS0746: Invalid anonymous type member declarator. Anonymous type members    must be declared with a member assignment, simple name or member access. 

It works when I use data_details, but I guess it need to be starting with "data-" as per the spec.

My questions:

• Is there any way to get this working and use HTML5 data attributes with Html.ActionLink or similar Html helpers ?
• Is there any other alternative mechanism to attach custom data to an element? This data is to be processed later by JS.

Answer 1

This problem has been addressed in ASP.Net MVC 3. They now automatically convert underscores in html attribute properties to dashes. They got lucky on this one, as underscores are not legal in html attributes, so MVC can confidently imply that you'd like a dash when you use an underscore.

For example:

@Html.TextBoxFor(vm => vm.City, new { data_bind = "foo" }) 

will render this in MVC 3:

<input data-bind="foo" id="City" name="City" type="text" value="" /> 

If you're still using an older version of MVC, you can mimic what MVC 3 is doing by creating this static method that I borrowed from MVC3's source code:

public class Foo {     public static RouteValueDictionary AnonymousObjectToHtmlAttributes(object htmlAttributes) {         RouteValueDictionary result = new RouteValueDictionary();         if (htmlAttributes != null) {             foreach (System.ComponentModel.PropertyDescriptor property in System.ComponentModel.TypeDescriptor.GetProperties(htmlAttributes)) {                 result.Add(property.Name.Replace('_', '-'), property.GetValue(htmlAttributes));             }         }         return result;     } } 

And then you can use it like this:

<%: Html.TextBoxFor(vm => vm.City, Foo.AnonymousObjectToHtmlAttributes(new { data_bind = "foo" })) %> 

and this will render the correct data-* attribute:

<input data-bind="foo" id="City" name="City" type="text" value="" />