Populate comma separated string to multi select ListBox in Asp.net - C#

Question

I have a List Box which i want to get selected from a comma separated string but my code is not working.

ASPX:

<asp:ListBox ID="ListBox1" runat="server" SelectionMode="Multiple">
    <asp:ListItem Value="1">aaa</asp:ListItem>
    <asp:ListItem Value="2">bbb</asp:ListItem>
    <asp:ListItem Value="3">ccc</asp:ListItem>
    <asp:ListItem Value="4">ddd</asp:ListItem>
    <asp:ListItem Value="5">eee</asp:ListItem>
    <asp:ListItem Value="6">fff</asp:ListItem>
</asp:ListBox>

ASPX.CS: (Code)

string listboxvalues = "2,1,5";
for (int i = 0; i < ListBox1.Items.Count; i++)
{
    foreach (string category in listboxvalues.ToString().Split(','))
    {
        if (category != ListBox1.Items[i].Value) continue;
            ListBox1.Items[i].Selected = true;
            break;
    }
}

Expected Result: (The expected result is what i am expecting but the code is not selecting anything)

<asp:ListBox ID="ListBox1" runat="server" SelectionMode="Multiple">
    <asp:ListItem Value="1" Selected="True">aaa</asp:ListItem>
    <asp:ListItem Value="2" Selected="True">bbb</asp:ListItem>
    <asp:ListItem Value="3">ccc</asp:ListItem>
    <asp:ListItem Value="4">ddd</asp:ListItem>
    <asp:ListItem Value="5" Selected="True">eee</asp:ListItem>
    <asp:ListItem Value="6">fff</asp:ListItem>
</asp:ListBox>

What do you mean by my code is not working? This code as it is seems to select 1 2 and 5 in the ListBox — Jaqen H'ghar
– Jaqen H'ghar, Commented Oct 4, 2017 at 21:43
The expected result is what i am expecting but the code is not selecting anything — orbnexus
– orbnexus, Commented Oct 4, 2017 at 21:47
Where did you place the code behind? in the Page_Load? I just tested it and it worked... Are you sure there's nothing else that deselects the items? — Jaqen H'ghar
– Jaqen H'ghar, Commented Oct 4, 2017 at 21:53

NoobProgger · Accepted Answer · 2017-10-04 22:48:19Z

1

ASPX.CS: (Code)

string listboxvalues = "2,1,5";

//declare a list

List<string> items = new List<string>()

for (int i = 0; i < ListBox1.Items.Count; i++)
{
    foreach (string category in listboxvalues.ToString().Split(','))
    {
        if (category != ListBox1.Items[i].Value) continue;
            items.Add(category);
            break;
    }
}

//then in your ListBox1

listBox1.DataSource = items;
        listBox1.DisplayMember = "Item";
        listBox1.ValueMember = "Value";

answered Oct 4, 2017 at 22:48

NoobProgger

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1 Comment

Kiquenet Over a year ago

List<string> items not have Item or Value properties?

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Populate comma separated string to multi select ListBox in Asp.net - C#

ASPX:

ASPX.CS: (Code)

Expected Result: (The expected result is what i am expecting but the code is not selecting anything)

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ASPX:

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