Question

I am trying to pass the selected items from a checkboxlist in asp.net (vs 2005/.net 2.0) as a concatenated string.

Currently my .aspx is

        <asp:CheckBoxList id="checkbox1" AutoPostBack="False" AppendDataBoundItems="true" CellPadding="5" CellSpacing="5" RepeatColumns="1" RepeatDirection="Vertical" RepeatLayout="Flow" TextAlign="Right" runat="server">
            <asp:ListItem Value="1">Carrots</asp:ListItem>
            <asp:ListItem Value="2">Lettuce</asp:ListItem>
            <asp:ListItem Value="3">Olives</asp:ListItem>
            <asp:ListItem Value="4">Onions</asp:ListItem>
            <asp:ListItem Value="5">Tomato</asp:ListItem>
            <asp:ListItem Value="6">Pickles</asp:ListItem>
        </asp:CheckBoxList>

And the .aspx.vb is (inside the Protected Sub for submit)

    For Each li As ListItem In checkbox1.Items
        If li.Selected = True Then
            checkbox1.Text = checkbox1.Text + "," + li.Text
        End If
    Next

Which is written to the db via

checkbox1.Text = dv(0)("Salad").ToString()

When I select and save, I am currently getting an error

Server Error in ‘/’ Application.

‘checkbox1’ has a SelectedValue which is invalid because it does not exist in the list of items.

Parameter name: value

Any thoughts on how to concatenate the selected checkbox items

For example, if some selects Carrots, Lettuce, and Tomato;

checkbox1 = 1,2,5

Answer 1

I don’t think you are assigning to a variable like you describe you are returning.

string list = "";
For Each li As ListItem In chkQ4.Items
        If li.Selected = True Then
            list = list + "," + li.Text
        End If
    Next

is how you should write the line above.

In C# using linq, I would write

var list =  checkbox1.Items
.Cast<ListItem>()
.Where(item => item.Selected == true)
.Select(item => item.Value);
var result = string.Join(",",list);

which I believe is the following in VB

Dim list = checkbox1.Items.Cast(Of ListItem)().Where(Function(item) item.Selected = True).[Select](Function(item) item.Value)
Dim result = String.Join(",", list.ToArray())