ASP:ListBox Get Selected Items – One Liner?

I am trying to get the selected items of an asp:ListBox control and put them in a comma delimited string. There has got to be a simpler way of doing this then:

foreach (ListItem listItem in lbAppGroup.Items)
{
    if (listItem.Selected == true)
    {
        Trace.Warn("Selected Item", listItem.Value);
    }
}

Is there a way to get this into one line? like my pseudo code here:

string values = myListBox.SelectedItems;

I am using ASP.NET and C# 3.5.

Thanks for any help!!

Answers:

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Method 1

Using LINQ:

string values = String.Join(", ", lbAppGroup.Items.Cast<ListItem>()
                                                  .Where(i => i.Selected)
                                                  .Select(i => i.Value));

Method 2

I don’t think there is anything built in but you could do something like this:

  <asp:ListBox runat="server" ID="listBox" SelectionMode="Multiple">
    <asp:ListItem Selected="True" Text="text1" Value="value1"></asp:ListItem>
    <asp:ListItem Selected="false" Text="text2" Value="value2"></asp:ListItem>
    <asp:ListItem Selected="True" Text="text3" Value="value3"></asp:ListItem>
    <asp:ListItem Selected="True" Text="text4" Value="value4"></asp:ListItem>
</asp:ListBox>

    IEnumerable<string> selectedValues = from item in listBox.Items.Cast<ListItem>()
                                             where item.Selected
                                             select item.Text;

        string s = string.Join(",", selectedValues);

Method 3

var selectedQuery = listBox.Items.Cast<ListItem>().Where(item => item.Selected); 
string selectedItems =  String.Join(",", selectedQuery).TrimEnd();

Method 4

Actually there IS something built in:

ListBox.getSelectedItems

http://msdn.microsoft.com/en-us/library/aa297606(v=vs.60).aspx

Method 5

Another way is to use the Request Form object which contains everything that was posted back. eg:

string values = Request.Form(lbAppGroup.UniqueID);  //returns "a,b" if they were selected

This by default returns a comma delimited list of selected items.
I sometimes use this way when I don’t want or need to bind the data again but still want to get the selected values for processing.

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0