asp.net - MVC SelectList combining multiple columns in text field

Question

How would I generate a select list, where the text field, is made up of two or more text columns, eg: Where I have a Description and Rate field in my database, I want to combine these to show:

Large--￡200
Medium--￡150
Small--￡100

Controller code is:

 var stands = db.Stands.Where(s => s.ExhibitorID == null).ToList();
 ViewBag.StandID = new SelectList(stands,"StandID", "Description" + "-- ￡" + "Rate");

...and my view is (currently):

    <div class="editor-field"> 
        @Html.DropDownList("StandID", "--Select--") 
    </div> 

...but the "Description" + "-- ￡" + "Rate"); won't run:

DataBinding: 'System.Data.Entity.DynamicProxies.Stand_63F8C9F623B3C0E57D3008A57081AFCD9C39E1A6B79B0380B60840F1EFAE9DB4' does not contain a property with the name 'Description--￡Rate'.

Thanks for any help,

Mark

Answer 1

You could create a new anonymous class using a simple LINQ projection, and then use the SelectList(IEnumerable, string, string) constructor overload to specify the value and text fields to be used for the <option> elements i.e.:

var stands = 
  db.Stands
    .Where(s => s.ExhibitorID == null)
    .Select(s => new 
     { 
       StandID = s.StandID,
       Description = string.Format("{0}-- ￡{1}", s.Description, s.Rate) 
     })
    .ToList();

ViewBag.StandID = new SelectList(stands, "StandID", "Description")

Edit

In C#6 and later, string interpolation makes for better reading than string.Format

   ...
   Description = $"{s.Description}-- ￡{s.Rate}"

If you project to a strong ViewModel class name (instead of to an anonymous class), you will undoubtedly want to replace the magic strings with the safety of the nameof operator:

ViewBag.StandID = new SelectList(stands, nameof(Stand.StandID), nameof(Stand.Description));