Handling null values in asp.net MVC dropdowns

Question

How do I create a dropdown in ASP.NET MVC that can handle a null value?

The application is a lookup field in a database, where the primary key is in a lookup table, i.e. Categories, and the foreign key is in another table, i.e. CategoryID, but CategoryID is OPTIONAL (i.e. it can contain a null).

I would imagine the generated markup in the user's web page would look something like this:

<select id="foo">
    <option value="">(Not Specified)</option>
    <option value="1">Alpha</option>
    <option value="2">Bravo</option>
    <option value="3">Charlie</option>
</select>

Can I do something like this without having to write a custom HtmlHelper? Would this bind properly to the underlying model when the time comes to save?

Answer 1

You don't need to write a helper. It already exists. Use one of the Html.Select overloads which takes an optionLabel argument. Set that to "(Not Specified)".

Answer 2

Also, whatever field you are binding to must be nullable - in this case, either a string, or a nullable int.