Set dynamic ErrorMessage in RequiredFieldValidator in ASP.Net ListView

Hi nauna,

Check this example. Now please take its reference and correct your code.

HTML

<asp:ListView ID="lvCustomers" runat="server">
    <ItemTemplate>
        <asp:TextBox ID="txtName" runat="server" BorderColor="#CCCCCC" Text='<%#Eval("Name") %>'></asp:TextBox>
        <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" 
            ErrorMessage='<%#String.Format("{0} Required", Container.DataItemIndex +1)%>'
            ControlToValidate="txtName" ValidationGroup="quiz" CssClass="required"></asp:RequiredFieldValidator>
        <br />
        <br />
    </ItemTemplate>
</asp:ListView>
<asp:Button Text="Validate" runat="server" ValidationGroup="quiz" />

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!this.IsPostBack)
    {
        System.Data.DataTable dt = new System.Data.DataTable();
        dt.Columns.AddRange(new System.Data.DataColumn[] {
            new System.Data.DataColumn("Id"), new System.Data.DataColumn("Name") });
        dt.Rows.Add(1, "John Hammond");
        dt.Rows.Add(2, "Mudassar Khan");
        dt.Rows.Add(3, "Suzanne Mathews");
        dt.Rows.Add(4, "");
        lvCustomers.DataSource = dt;
        lvCustomers.DataBind();
    }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    If Not Me.IsPostBack Then
        Dim dt As System.Data.DataTable = New System.Data.DataTable()
        dt.Columns.AddRange(New Data.DataColumn() {
                            New Data.DataColumn("Id"), New Data.DataColumn("Name")})
        dt.Rows.Add(1, "John Hammond")
        dt.Rows.Add(2, "Mudassar Khan")
        dt.Rows.Add(3, "Suzanne Mathews")
        dt.Rows.Add(4, "")
        lvCustomers.DataSource = dt
        lvCustomers.DataBind()
    End If
End Sub

Screenshot