ASP.NET MVC MultiSelect issue

I'm trying to create a listbox with multiple selected items but it doesn't work.

My model:

Function Edit(ByVal id As Integer) As ActionResult
 Dim vm As New ViewModels.NewsItemViewModel() With {
  .NewsItem = _
db.NewsItems.Include("NewsCategories").Single(Function(item) item.Id = id),
  .Categories = _
New MultiSelectList(db.Categories, "Id", "Category", .NewsItem.NewsCategories)
 }
 Return View(vm)
End Function

The first param of MultiSelectList is the list of Categories, the last param is the list of selected categories.

It doesn't work because nothing gets selected

<select id="NewsItem_NewsCategories" 
multiple="multiple" name="NewsItem.NewsCategories">
<option value="1">Politics</option>
<option value="2">Economy</option>
<option value="3">Sports</option>
</select>

Then I read somewhere that the last param expects a list of strings with the ids. So I modified my code

Function Edit(ByVal id As Integer) As ActionResult
 Dim vm As New ViewModels.NewsItemViewModel() With {
  .NewsItem = _
db.NewsItems.Include("NewsCategories").Single(Function(item) item.Id = id),
  .Categories = _
New MultiSelectList(db.Categories, "Id", "Category", .NewsItem.NewsCategories.Select(Function(c) c.id.ToString())
 }
 Return View(vm)
End Function

When I looked up the values during runtime I got some hope:

But the resulting HTML is the same as what I showed in my first html sample: nothing is selected.

Since the MVC code is open source you can view MultiSelectList's code: download here.

The code in the View:

<%: Html.ListBoxFor(Function(m) m.NewsItem.NewsCategories, Model.Categories)%>

ZippyV said:

The code in the View:

<%: Html.ListBoxFor(Function(m) m.NewsItem.NewsCategories, Model.Categories)%>

I have had my share of headache's with the HTML.ListBoxFor

One of the gotacha's is; don't put any ViewData[] or other stuff on your form that interferes with the name, ID's ect.

Here's how I use em, that I found works:

The SalesOpsManagers is just an IList<string>

And the viewdata is in the form of a selectlistitem, doesnt need to be multiselectlist item

hope this helps you

Maddus Mattus said:

ZippyV said:

*snip*

I have had my share of headache's with the HTML.ListBoxFor

 

One of the gotacha's is; don't put any ViewData[] or other stuff on your form that interferes with the name, ID's ect.

 

Here's how I use em, that I found works:

 

The SalesOpsManagers is just an IList<string>

 

<%

= Html.ListBoxFor(model => model.SalesOpsManagers, (IEnumerable<SelectListItem>)ViewData["TerritorySalesOpsManagers"], new { style = "width:250px;" })%>

 

And the viewdata is in the form of a selectlistitem, doesnt need to be multiselectlist item

 

hope this helps you

As you can see from my controller action, I don't put anything in the viewdata.

I've seen people creating a list of SelectListItem using LINQ but they are all in C# and I have no idea how to translate it to VB.NET.

Example:

var friendNames = 
 (from tweet in friendTweets
 select new SelectListItem
 {
  Text = tweet.ScreenName,
  Value = tweet.ScreenName
// Selected = True|False should also be filled in here
 })
 .ToList();

ZippyV said:

Maddus Mattus said:

*snip*

As you can see from my controller action, I don't put anything in the viewdata.

 

I've seen people creating a list of SelectListItem using LINQ but they are all in C# and I have no idea how to translate it to VB.NET.

 

Example:

var friendNames = 
 (from tweet in friendTweets
 select new SelectListItem
 {
  Text = tweet.ScreenName,
  Value = tweet.ScreenName
// Selected = True|False should also be filled in here
 })
 .ToList();

Dim friendNames = (From tweet In friendTweets _
                   Select New SelectListItem() With _
                   { _
                       .Text = tweet.ScreenName, _
                       .Value = tweet.ScreenName _
                   }).ToList()

This really ain't rocket science.

ZippyV said:

Maddus Mattus said:

*snip*

As you can see from my controller action, I don't put anything in the viewdata.

 

I've seen people creating a list of SelectListItem using LINQ but they are all in C# and I have no idea how to translate it to VB.NET.

 

Example:

var friendNames = 
 (from tweet in friendTweets
 select new SelectListItem
 {
  Text = tweet.ScreenName,
  Value = tweet.ScreenName
// Selected = True|False should also be filled in here
 })
 .ToList();

Zippy,

does the problem exist?

if so, can you post your asmx or aspx?