Programmatically selecting values in a list box

[JulesBos]

Hi,

I've got a list box on a web form which, when loaded, uses data from a text field in a database to determine which values should be selected. When the user presses save, the selections from the list box should be resaved to the text field.

This works fine if the user manually selects items from the list box, but if they don't make any changes and the list box shows just the selected items from the loading code then, when the user tries to resave, the selectedindex of the list box is showing as 0, even though the items are highlighted, so resave doesn't work.

Here's the code:

'Firstly to select values from the list box
If Not DataReader.GetValue(119) Is DBNull.Value Then
                'firstly get the values
                Dim fullString As String = DataReader.GetValue(119)
                'check if there is a comma separator in the string, if not then there's only one
                'value, so use that
                If InStr(fullString, ",") = 0 Then
                    Me.AdditionalEmailList.SelectedValue = fullString
                'otherwise we need to get each of the values by looping through the string
                Else
                    Dim charPosition As Integer
                    Dim listName As String
                    While fullString <> ""
                        If InStr(fullString, ",") = 0 Then
                            charPosition = fullString.Length
                        Else
                            charPosition = fullString.IndexOf(",")
                        End If
                        listName = Left(fullString, charPosition)
                        fullString = fullString.Remove(0, charPosition)
                        If fullString <> "" Then
                            fullString = fullString.Remove(0, 1)
                        End If
                        'now we have a name, make sure that name is selected
                        Dim item As ListItem = Me.AdditionalEmailList.Items.FindByValue(listName)
                            If Not item Is Nothing Then
                                item.Selected = True
                            End If
                    End While
                End If
            End If

'now to resave the selected values on the list box
Dim entryString As String
        'get the selected values from the list box and concatenate them into one string
        'this is where I get the problem - selectedindex is 0
        If Me.AdditionalEmailList.SelectedIndex <> 0 Then
            Dim li As ListItem
            entryString = ""
            For Each li In Me.AdditionalEmailList.Items
                If li.Selected = True Then
                    entryString += li.Value + ","
                End If
            Next
            'now remove the final comma
            Dim finalChar As Integer = entryString.Length
            entryString = entryString.Remove(finalChar - 1, 1)
        End If

Thanks in advance.

 

[JulesBos]

I have solved my own problem! When loading the listbox for the first time (before any data is selected), I was selecting a default value of "". I've removed this value and instead of using If listbox.selectedindex <> 0, I used If listbox.selectedindex <> -1, and that works fine.