Retrieve selected value from DropDownList on Button click using C# and VB.Net in ASP.Net

Hi mkhader,

As per your query i have create the sample. If you have any doubt Please revert me back. Below is the sample.

HTML

<asp:Repeater ID="repCustomer" runat="server" OnItemDataBound="repCustomer_ItemDataBound">
    <ItemTemplate>
        <table>
            <tr>
                <td>
                    Country:<asp:DropDownList ID="ddlCountry" runat="server" OnSelectedIndexChanged="ddlCountry_SelectedIndexChanged"
                        AutoPostBack="true" AppendDataBoundItems="true">
                        <asp:ListItem Text="Select" Value="0" />
                    </asp:DropDownList>
                </td>
                <td>
                    State:
                    <asp:DropDownList ID="ddlStates" runat="server" AppendDataBoundItems="true">
                        <asp:ListItem Text="Select" Value="0" />
                    </asp:DropDownList>
                </td>
                <td>
                    <asp:Button Text="Save" runat="server" ID="btnSave" OnClick="Save" />
                </td>
            </tr>
        </table>
    </ItemTemplate>
</asp:Repeater>

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataTable dt1 = new DataTable();
        dt1.Columns.Add("Name", typeof(string));
        dt1.Rows.Add("Salman");
        repCustomer.DataSource = dt1;
        repCustomer.DataBind();

    }
}

protected void repCustomer_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
    DataTable dt = new DataTable();
    dt.Columns.Add("ID", typeof(int));
    dt.Columns.Add("Country", typeof(string));
    dt.Rows.Add(1, "India");
    dt.Rows.Add(2, "Pakistan");
    dt.Rows.Add(3, "SriLanka");
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        DropDownList ddlCountry = (DropDownList)e.Item.FindControl("ddlCountry");
        ddlCountry.DataSource = dt;
        ddlCountry.DataTextField = "Country";
        ddlCountry.DataValueField = "ID";
        ddlCountry.DataBind();
    }
}

protected void ddlCountry_SelectedIndexChanged(object sender, EventArgs e)
{
    RepeaterItem row = (RepeaterItem)(sender as DropDownList).NamingContainer;
    DropDownList ddlStates = (DropDownList)row.FindControl("ddlStates");
    int ddlCountry = Convert.ToInt32(((DropDownList)row.FindControl("ddlCountry")).SelectedValue);
    DataTable dtStates = new DataTable();
    dtStates.Columns.Add("ID", typeof(int));
    dtStates.Columns.Add("States", typeof(string));
    dtStates.Columns.Add("CountryId", typeof(int));
    dtStates.Rows.Add(1, "Bihar", 1);
    dtStates.Rows.Add(2, "U.P", 1);
    dtStates.Rows.Add(3, "Lahor", 2);
    dtStates.Rows.Add(4, "Pesawar", 2);
    dtStates.Rows.Add(5, "Colombo", 3);
    DataRow[] rows = dtStates.Select("CountryId = " + ddlCountry);
    DataTable dtFinal = dtStates.Clone();
    foreach (DataRow dr in rows) { dtFinal.Rows.Add(dr.ItemArray); }
    ddlStates.Items.Clear();
    ddlStates.DataSource = dtFinal;
    ddlStates.DataTextField = "States";
    ddlStates.DataValueField = "ID";
    ddlStates.DataBind();
}

protected void Save(object sender, EventArgs e)
{
    Button btn = (sender as Button);
    string country = (btn.NamingContainer.FindControl("ddlCountry") as DropDownList).SelectedItem.Text;
    string state = (btn.NamingContainer.FindControl("ddlStates") as DropDownList).SelectedItem.Text;
    Response.Write(string.Format("Country : {0}<br/>State : {1}", country, state));
}

VB.Net

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        Dim dt1 As New DataTable()
        dt1.Columns.Add("Name", GetType(String))
        dt1.Rows.Add("Salman")
        repCustomer.DataSource = dt1

        repCustomer.DataBind()
    End If
End Sub

Protected Sub repCustomer_ItemDataBound(sender As Object, e As RepeaterItemEventArgs)
    Dim dt As New DataTable()
    dt.Columns.Add("ID", GetType(Integer))
    dt.Columns.Add("Country", GetType(String))
    dt.Rows.Add(1, "India")
    dt.Rows.Add(2, "Pakistan")
    dt.Rows.Add(3, "SriLanka")
    If e.Item.ItemType = ListItemType.Item OrElse e.Item.ItemType = ListItemType.AlternatingItem Then
        Dim ddlCountry As DropDownList = DirectCast(e.Item.FindControl("ddlCountry"), DropDownList)
        ddlCountry.DataSource = dt
        ddlCountry.DataTextField = "Country"
        ddlCountry.DataValueField = "ID"
        ddlCountry.DataBind()
    End If
End Sub

Protected Sub ddlCountry_SelectedIndexChanged(sender As Object, e As EventArgs)
    Dim row As RepeaterItem = DirectCast(TryCast(sender, DropDownList).NamingContainer, RepeaterItem)
    Dim ddlStates As DropDownList = DirectCast(row.FindControl("ddlStates"), DropDownList)
    Dim ddlCountry As Integer = Convert.ToInt32(DirectCast(row.FindControl("ddlCountry"), DropDownList).SelectedValue)
    Dim dtStates As New DataTable()
    dtStates.Columns.Add("ID", GetType(Integer))
    dtStates.Columns.Add("States", GetType(String))
    dtStates.Columns.Add("CountryId", GetType(Integer))
    dtStates.Rows.Add(1, "Bihar", 1)
    dtStates.Rows.Add(2, "U.P", 1)
    dtStates.Rows.Add(3, "Lahor", 2)
    dtStates.Rows.Add(4, "Pesawar", 2)
    dtStates.Rows.Add(5, "Colombo", 3)
    Dim rows As DataRow() = dtStates.Select("CountryId = " & ddlCountry)
    Dim dtFinal As DataTable = dtStates.Clone()
    For Each dr As DataRow In rows
        dtFinal.Rows.Add(dr.ItemArray)
    Next
    ddlStates.Items.Clear()
    ddlStates.DataSource = dtFinal
    ddlStates.DataTextField = "States"
    ddlStates.DataValueField = "ID"
    ddlStates.DataBind()
End Sub

Protected Sub Save(sender As Object, e As EventArgs)
    Dim btn As Button = TryCast(sender, Button)
    Dim country As String = TryCast(btn.NamingContainer.FindControl("ddlCountry"), DropDownList).SelectedItem.Text
    Dim state As String = TryCast(btn.NamingContainer.FindControl("ddlStates"), DropDownList).SelectedItem.Text
    Response.Write(String.Format("Country : {0}<br/>State : {1}", country, state))
End Sub

Screenshot