Chapter 5: Edit Album DropDownList

Andy W · February 7th, 2012, 11:01 PM

After some time trying get the example on Pg. 105 working, I'm crying Uncle!
In debug I can see the ViewBag.Genres populated with SelectListItems, but I can't figure out how to get them into a SelectList that DropDownList can use. Thanks, to anyone who might shed light on this.

My Controller code is (straight from the book)

Code:

// ~/Controllers/AlbumController.cs

{
  public class AlbumController : Controller
  {
    private MusicStoreDB storeDB = new MusicStoreDB();

    // 
    // GET: /Album/Edit/#    
    public ActionResult Edit(int id)
    {
      var album = storeDB.Albums.Single(a => a.AlbumId == id);

      // Page 105 - Use LINQ to project Generes into SelectListItem
      ViewBag.Genres = storeDB.Genres
        .OrderBy(g => g.Name)
        .AsEnumerable()
        .Select(g => new SelectListItem
        {
          Text = g.Name,
          Value = g.GenreId.ToString(),
          Selected = album.GenreId == g.GenreId
        });
      return View(album);
    }
  }
}

My View Code is ...

Code:

@* ~/Views/Album/Edit.cshtml  *@

@model MvcMusicStore.Models.Album
@using (Html.BeginForm())
{
  @Html.ValidationSummary(excludePropertyErrors: true)
  <fieldset>
    <legend>Edit Album</legend>
    <p>
      @Html.Label("GenreId")
      @Html.DropDownList("GenreId", ViewBag.Genres as SelectList)  
    </p>
    <p>    
      @Html.Label("Title")
      @Html.TextBox("Title", Model.Title)
  
    </p>
    <input type="submit" value="Save" />
  </fieldset>
}

The view throws an exception at @Html.DropDownList ..

Code:

The ViewData item that has the key 'GenreId' is of type 'System.Int32' but must be of type 'IEnumerable<SelectListItem>'.

bh81 · February 9th, 2012, 09:58 AM

Does

@Html.DropDownList("GenreId", (IEnumerable<SelectListItem>)ViewBag.Genres)

help?

(A bit blind leading the blind here.....I had something similar and it worked).

Andy W · February 10th, 2012, 04:21 PM

Thanks, your suggestion worked!