OK.. phew. Playing with data grids for the past few days has been fun and a
huge learning experience..
My problem. I have a requirement to display a gird with a gird. Within the
embedded grid, theres a requirement to show a drop down menu list (this is a
control I downloaded online) in one of the columns. For the purposes of this
question, Ive implemented the drop down menu as a drop down list instead.
Ive got all this working at this point. Heres my problem:
1) When a person selects an item in the drop down list, I need the server to
autopost back and fire an event which I can handle on the sever side.
2) On the server side, I need to be able to figure out which drop down list
the event was fired for and what the selected value is.
Ive implemented the display of the column showing the drop down list in a
custom built DataGridColumn. All the code is below.
My Question:
1) How do I setup ONE postback event handler for ALL the drop downlist
controls being rendered dynamically in the embedded grid?
2) The event handler must be in the code-behind code that uses the custom
built DataGridColumn and should not be in the DataGridColumn code itself.
2) How do I figure out in that one event handler method, the drop down list
that threw the event, and the value of the selected item.
If you look towards the end of the method
CustomerDataGrid_OnItemDataBound(object sender, DataGridItemEventArgs e),
you'll find the code where I programmatically attach the new column. The
custom col code itself is the last snippet of code in this email.
Appreciate anyones help.
Girish
----------------
ASPX CODE
---------------
<%@ Page language="c#" Inherits="MasterDetail.CustomerOrderDataGrid"
EnableViewState="False" CodeBehind="CustomerOrderDataGrid.aspx.cs"
AutoEventWireup="false" %>
<HTML>
<LINK REL=StyleSheet HREF="menu.css" TYPE="text/css" />
<body style="FONT: x-small Verdana, Arial, sans-serif">
<!-- Begin Web Form -->
<form id="CustomerOrderDataGrid" method="post" runat="server">
<p><a href="/DayOfDotNet/">Parent Directory</a></p>
<!-- Begin DataGrid -->
<asp:DataGrid id="CustomerDataGrid" runat="server"
AutoGenerateColumns="False" CellPadding="2"
CellSpacing="0" Font-Names="Verdana, Arial, sans-serif"
BorderColor="Black" BorderWidth="1"
GridLines="Horizontal"
OnItemDataBound="CustomerDataGrid_OnItemDataBound" EnableViewState="False">
<AlternatingItemStyle BackColor="Tan"></AlternatingItemStyle>
<ItemStyle Font-Size="X-Small"></ItemStyle>
<HeaderStyle Font-Size="Small" Font-Names="Arial" Font-Bold="True"
ForeColor="White" BackColor="Maroon"></HeaderStyle>
<Columns>
<asp:BoundColumn Visible="False"
DataField="CustomerID"></asp:BoundColumn>
<asp:HyperLinkColumn
DataTextField="CustomerID"
DataNavigateUrlField="CustomerID"
DataNavigateUrlFormatString="OrderDetailDataGrid.a spx?customerid={0}"
HeaderText="ID"
ItemStyle-VerticalAlign="Top" />
<asp:TemplateColumn HeaderText="Customer">
<ItemStyle VerticalAlign="Top"></ItemStyle>
<ItemTemplate>
<b>
<%# DataBinder.Eval(Container.DataItem, "CompanyName") %>
</b>
<br>
<%# DataBinder.Eval(Container.DataItem, "Address" ) %>
<br>
<%# DataBinder.Eval(Container.DataItem, "City" ) %>
,
<%# DataBinder.Eval(Container.DataItem, "Region") %>
<%# DataBinder.Eval(Container.DataItem, "PostalCode" ) %>
<br>
<br>
<%# DataBinder.Eval(Container.DataItem, "ContactName" ) %>
<br>
<%# DataBinder.Eval(Container.DataItem, "ContactTitle" ) %>
<br>
<%# DataBinder.Eval(Container.DataItem, "Phone" ) %>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn ItemStyle-VerticalAlign="Top"
HeaderText="Orders">
<%-- Embedded DataGrid will go here --%>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>
<!-- End DataGrid -->
</form>
<!-- End Web Form -->
</body>
</HTML>
-------------------
CODE BEHIND
------------------
using System;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
using System.Configuration;
namespace MasterDetail
{
public class CustomerOrderDataGrid : System.Web.UI.Page
{
protected DataGrid CustomerDataGrid;
private DataSet ds = new DataSet();
private void Page_Load(object sender, System.EventArgs e)
{
string sqlStmt = "SELECT top 2 * FROM Customers; SELECT * FROM Orders";
string conString =
"server=localhost;database=Northwind;uid=sa;pwd=ti etronix;";
SqlDataAdapter sda = new SqlDataAdapter(sqlStmt, conString);
sda.Fill(ds);
ds.Tables[0].TableName = "Customers";
ds.Tables[1].TableName = "Orders";
CustomerDataGrid.DataSource = ds.Tables["Customers"];
CustomerDataGrid.DataBind();
}
//Use the OnItemDataBound event handler to dynamically add an embedded
DataGrid
protected void CustomerDataGrid_OnItemDataBound(object sender,
DataGridItemEventArgs e)
{
//When each row is created in the DataGrid, eval the ItemType
if(e.Item.ItemType == ListItemType.Item ||
e.Item.ItemType == ListItemType.AlternatingItem)
{
//If the ItemType is Item or AlternatingItem,
//Create a new DataGrid object named OrdersDataGrid
DataGrid OrdersDataGrid = new DataGrid();
//Format the DataGrid to look cool.
OrdersDataGrid.BorderWidth = (Unit)1;
OrdersDataGrid.CellPadding = 4;
OrdersDataGrid.CellSpacing = 0;
OrdersDataGrid.GridLines = GridLines.Horizontal;
OrdersDataGrid.BorderColor = Color.FromName("Black");
OrdersDataGrid.ItemStyle.Font.Name = "Verdana";
OrdersDataGrid.ItemStyle.Font.Size = FontUnit.XSmall;
OrdersDataGrid.AlternatingItemStyle.BackColor =
Color.FromName("LightGray");
OrdersDataGrid.ShowHeader = true;
OrdersDataGrid.HeaderStyle.BackColor = Color.FromName("Black");
OrdersDataGrid.HeaderStyle.ForeColor = Color.FromName("White");
OrdersDataGrid.HeaderStyle.Font.Bold = true;
OrdersDataGrid.HeaderStyle.Font.Size = FontUnit.XSmall;
//Do not autogenerate columns.
OrdersDataGrid.AutoGenerateColumns = false;
//Add a series of BoundColumns
//Order ID
BoundColumn bc = new BoundColumn();
//Set the BoundColumn Values
bc.HeaderText = "Order ID";
bc.DataField = "OrderID";
bc.ItemStyle.Wrap = false;
//Add the BoundColumn to the OrdersDataGrid.
OrdersDataGrid.Columns.Add(bc);
//Order Date
bc = new BoundColumn();
bc.HeaderText = "Order Date";
bc.DataField = "OrderDate";
bc.DataFormatString="{0:d}";
bc.ItemStyle.Wrap = false;
OrdersDataGrid.Columns.Add(bc);
//Required Date
bc = new BoundColumn();
bc.HeaderText = "Required Date";
bc.DataField = "RequiredDate";
bc.DataFormatString="{0:d}";
bc.ItemStyle.Wrap = false;
OrdersDataGrid.Columns.Add(bc);
//Shipped Date
bc = new BoundColumn();
bc.HeaderText = "Shipped Date";
bc.DataField = "ShippedDate";
bc.DataFormatString="{0:d}";
bc.ItemStyle.Wrap = false;
OrdersDataGrid.Columns.Add(bc);
// ADD THE CUSTOM BUILT COL HERE
DropDownListColumn DDLC = new DropDownListColumn();
DDLC.HeaderText = "My DDL";
OrdersDataGrid.Columns.Add(DDLC);
//End BoundColumns
//Get the Authors DataView and filter it for the current ISBN
DataView _orders = ds.Tables["Orders"].DefaultView;
_orders.RowFilter = "CustomerID='" + e.Item.Cells[0].Text + "'";
//Bind the DataGrid.
OrdersDataGrid.DataSource = _orders;
OrdersDataGrid.DataBind();
e.Item.Cells[3].Controls.Add(OrdersDataGrid);
}
}
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form Designer.
//
InitializeComponent();
base.OnInit(e);
}
private void InitializeComponent()
{
this.Load += new System.EventHandler(this.Page_Load);
}
}
}
----------------------------------
Custom built data Grid col code
-----------------------------------
using System;
using System.Web.UI.WebControls;
namespace MasterDetail
{
public class DropDownListColumn : DataGridColumn
{
public DropDownListColumn() : base()
{
}
public override void InitializeCell(TableCell cell, int columnIndex,
ListItemType itemType)
{
base.InitializeCell(cell, columnIndex, itemType);
switch (itemType)
{
case ListItemType.EditItem:
case ListItemType.Item:
case ListItemType.AlternatingItem:
case ListItemType.SelectedItem:
cell.DataBinding += new EventHandler(this.ItemDataBinding);
DropDownList DLL = new DropDownList();
cell.Controls.Add( DLL );
break;
case ListItemType.Header:
break;
}
}
private void ItemDataBinding(object sender, EventArgs e)
{
TableCell cell = (TableCell)sender;
DropDownList DDL1 = (DropDownList)cell.Controls[0];
DDL1.Items.Add(new ListItem("one","1"));
DDL1.Items.Add(new ListItem("two","2"));
DDL1.Items.Add(new ListItem("three","3"));
}
}
}
Custom build DataGridColumn event problem 
