Populate DropDownList in nested GridView in ASP.Net

Hi Warren,

Please refer below sample.

HTML

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
    $("[src*=plus]").live("click", function () {
        $(this).closest("tr").after("<tr><td></td><td colspan = '999'>" + $(this).next().html() + "</td></tr>")
        $(this).attr("src", "images/minus.png");
    });
    $("[src*=minus]").live("click", function () {
        $(this).attr("src", "images/plus.png");
        $(this).closest("tr").next().remove();
    });
</script>
<asp:GridView ID="gvCustomers" runat="server" AutoGenerateColumns="false" CssClass="Grid"
    DataKeyNames="CustomerID" OnRowDataBound="OnRowDataBound">
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <img alt="" style="cursor: pointer" src="images/plus.png" />
                <asp:Panel ID="pnlOrders" runat="server" Style="display: none">
                    <asp:GridView ID="gvOrders" runat="server" AutoGenerateColumns="false" CssClass="ChildGrid">
                        <Columns>
                            <asp:TemplateField HeaderText="OrderId">
                                <ItemTemplate>
                                    <asp:DropDownList ID="ddlOrderId" runat="server">
                                    </asp:DropDownList>
                                </ItemTemplate>
                            </asp:TemplateField>
                        </Columns>
                    </asp:GridView>
                </asp:Panel>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:BoundField ItemStyle-Width="150px" DataField="ContactName" HeaderText="Contact Name" />
        <asp:BoundField ItemStyle-Width="150px" DataField="City" HeaderText="City" />
    </Columns>
</asp:GridView>

Namespaces

C#

using System.Configuration;
using System.Data;
using System.Data.SqlClient;

Vb.Net

Imports System.Data.SqlClient
Imports System.Data

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        gvCustomers.DataSource = GetData("select top 10 * from Customers");
        gvCustomers.DataBind();
    }
}

private static DataTable GetData(string query)
{
    string strConnString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(strConnString))
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = query;
            using (SqlDataAdapter sda = new SqlDataAdapter())
            {
                cmd.Connection = con;
                sda.SelectCommand = cmd;
                using (DataSet ds = new DataSet())
                {
                    DataTable dt = new DataTable();
                    sda.Fill(dt);
                    return dt;
                }
            }
        }
    }
}

protected void OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        string customerId = gvCustomers.DataKeys[e.Row.RowIndex].Value.ToString();
        GridView gvOrders = e.Row.FindControl("gvOrders") as GridView;
        gvOrders.DataSource = GetData(string.Format("select top 3 * from Orders where CustomerId='{0}'", customerId));
        gvOrders.DataBind();
        foreach (GridViewRow row in gvOrders.Rows)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                DropDownList ddlOrderId = row.FindControl("ddlOrderId") as DropDownList;
                ddlOrderId.DataSource = GetData(string.Format("select top 3 OrderId, OrderDate from Orders where CustomerId='{0}'", customerId));
                ddlOrderId.DataTextField = "OrderId";
                ddlOrderId.DataValueField = "OrderDate";
                ddlOrderId.DataBind();
            }
        }
    }
}

VB.Net

Protected Sub Page_Load(sender As Object, e As EventArgs) Handles Me.Load
    If Not IsPostBack Then
        gvCustomers.DataSource = GetData("select top 10 * from Customers")
        gvCustomers.DataBind()
    End If
End Sub

Private Shared Function GetData(query As String) As DataTable
    Dim strConnString As String = ConfigurationManager.ConnectionStrings("constr").ConnectionString
    Using con As New SqlConnection(strConnString)
        Using cmd As New SqlCommand()
            cmd.CommandText = query
            Using sda As New SqlDataAdapter()
                cmd.Connection = con
                sda.SelectCommand = cmd
                Using ds As New DataSet()
                    Dim dt As New DataTable()
                    sda.Fill(dt)
                    Return dt
                End Using
            End Using
        End Using
    End Using
End Function

Protected Sub OnRowDataBound(ByVal sender As Object, ByVal e As GridViewRowEventArgs)
    If e.Row.RowType = DataControlRowType.DataRow Then
        Dim customerId As String = gvCustomers.DataKeys(e.Row.RowIndex).Value.ToString()
        Dim gvOrders As GridView = TryCast(e.Row.FindControl("gvOrders"), GridView)
        gvOrders.DataSource = GetData(String.Format("select top 3 * from Orders where CustomerId='{0}'", customerId))
        gvOrders.DataBind()

        For Each row As GridViewRow In gvOrders.Rows

            If e.Row.RowType = DataControlRowType.DataRow Then
                Dim ddlOrderId As DropDownList = TryCast(row.FindControl("ddlOrderId"), DropDownList)
                ddlOrderId.DataSource = GetData(String.Format("select top 3 OrderId, OrderDate from Orders where CustomerId='{0}'", customerId))
                ddlOrderId.DataTextField = "OrderId"
                ddlOrderId.DataValueField = "OrderDate"
                ddlOrderId.DataBind()
            End If
        Next
    End If
End Sub

Screenshot