I also did that, but the dataset and dataview both have data contained in
them. The only thing that was strange is that DataItem was not set to any
object reference in the code-behind. But it indeed works for inline code
like <%# Container.DataItem %> in the .aspx file. So strange, I dont'
know why
Sorry, missed it.
I think the table name should be "Table1" rather than "Table". Anyway,
why don't you set a breakpoint on the line following the Fill call and
check what is in the dataset?
Eliyahu
I have done that in my last code post.
Maybe, that is not the key
point.
From the MSDN Library on DataGrid.DataMember property:
---
If the DataSet or DataViewManager contains only one DataTable, you
should set the DataMember to the TableName of that DataTable.
---
Just try this. It doesn't hurt.
Eliyahu
I suppose, there is no need to explicity set the DataMember, if there
is only one DataTable exists in the DataSet. The control will
automaitcally find the first DataTable to bind. The previous code I
posted withou specifying DataMember worked fine in my computer
Additionally, I've just followed what you have mentioned, accessing
the DataItem property in item-related events, both ItemCreated and
ItemDataBound. But they still doesn't work, keeping throwing
NullReferenceExceptions in both event handlers.
What a pity! I don't know what to do. It really frustrated me! Help,
please!
BTW: the whole program for Text.aspx was posted below, and just for
your information:
/// Test.aspx
<%@ Page language="c#" Codebehind="Test.aspx.cs"
AutoEventWireup="false" Inherits="CEIS.Test" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
<title>Test</title>
<meta content="Microsoft Visual Studio .NET 7.1" name="GENERATOR">
<meta content="C#" name="CODE_LANGUAGE">
<meta content="JavaScript" name="vs_defaultClientScript">
<meta content="
http://schemas.microsoft.com/intellisense/ie5"
name="vs_targetSchema">
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<asp:datagrid id="dataGrid" runat="server"></asp:datagrid></form>
</body>
</HTML>
/// Test.aspx.cs
using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;
namespace CEIS
{
/// <summary>
/// Summary description for Test.
/// </summary>
public class Test : System.Web.UI.Page
{
protected System.Data.SqlClient.SqlConnection testConnection;
protected System.Data.SqlClient.SqlCommand sqlSelectCommand1;
protected System.Data.SqlClient.SqlCommand sqlInsertCommand1;
protected System.Data.SqlClient.SqlCommand sqlUpdateCommand1;
protected System.Data.SqlClient.SqlCommand sqlDeleteCommand1;
protected System.Data.SqlClient.SqlDataAdapter testAdapter;
protected System.Data.DataSet dataSet;
protected System.Web.UI.WebControls.DataGrid dataGrid;
private void Page_Load(object sender, System.EventArgs e)
{
// Put user code to initialize the page here
testAdapter.Fill(dataSet);
dataGrid.DataMember = "Table";
dataGrid.DataSource = dataSet;
dataGrid.DataBind();
// Response.Write(dataGrid.Items[0].DataItem.ToString());
}
#region Web Form Designer generated code
override protected void OnInit(EventArgs e)
{
//
// CODEGEN: This call is required by the ASP.NET Web Form
Designer.
//
InitializeComponent();
base.OnInit(e);
}
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
System.Configuration.AppSettingsReader configurationAppSettings =
new System.Configuration.AppSettingsReader();
this.testConnection = new System.Data.SqlClient.SqlConnection();
this.sqlSelectCommand1 = new System.Data.SqlClient.SqlCommand();
this.sqlInsertCommand1 = new System.Data.SqlClient.SqlCommand();
this.sqlUpdateCommand1 = new System.Data.SqlClient.SqlCommand();
this.sqlDeleteCommand1 = new System.Data.SqlClient.SqlCommand();
this.testAdapter = new System.Data.SqlClient.SqlDataAdapter();
this.dataSet = new System.Data.DataSet();
((System.ComponentModel.ISupportInitialize)(this.dataSet)).BeginInit();
this.dataGrid.ItemCreated += new
System.Web.UI.WebControls.DataGridItemEventHandler(this.dataGrid_ItemCreated);
this.dataGrid.ItemDataBound += new
System.Web.UI.WebControls.DataGridItemEventHandler(this.dataGrid_ItemDataBound);
//
// testConnection
//
this.testConnection.ConnectionString =
((string)(configurationAppSettings.GetValue("testConnection.ConnectionString",
typeof(string))));
//
// sqlSelectCommand1
//
this.sqlSelectCommand1.CommandText = "SELECT Customers.* FROM
Customers";
this.sqlSelectCommand1.Connection = this.testConnection;
//
// testAdapter
//
this.testAdapter.DeleteCommand = this.sqlDeleteCommand1;
this.testAdapter.InsertCommand = this.sqlInsertCommand1;
this.testAdapter.SelectCommand = this.sqlSelectCommand1;
this.testAdapter.UpdateCommand = this.sqlUpdateCommand1;
//
// dataSet
//
this.dataSet.DataSetName = "testDataSet";
this.dataSet.Locale = new
System.Globalization.CultureInfo("en-US");
this.Load += new System.EventHandler(this.Page_Load);
((System.ComponentModel.ISupportInitialize)(this.dataSet)).EndInit();
}
#endregion
private void dataGrid_ItemCreated(object sender,
System.Web.UI.WebControls.DataGridItemEventArgs e)
{
// Response.Write(e.Item.DataItem.ToString());
}
private void dataGrid_ItemDataBound(object sender,
System.Web.UI.WebControls.DataGridItemEventArgs e)
{
// Response.Write(e.Item.DataItem.ToString());
}
}
}
Do you set DataMember property? You have to set it to the name of a
table in your dataset.
In what part of you code do you refer to
dataGrid.Items[0].DataItem? Typically, it should be in one of the
item-related events, like ItemDataBound or ItemCreated.
If it is not enough, post the relevant part of the .aspx file.
Don't sent attachments.
Eliyahu
And the .aspx file and .cs file is provided in the attachment for
your convenience, if necessary.
Thanks for your response. Here is the code fragment:
private void Page_Load(object sender, System.EventArgs e)
{
// Put user code to initialize the page here
testAdapter.Fill(dataSet);
dataGrid.DataSource = dataSet;
dataGrid.DataBind();
Response.Write(dataGrid.Items[0].DataItem.ToString()); // A
NullReferenceException will be thrown here!
}
The testAdapter executes an SelectCommand as 'select * from
Customers' on
the Northwind database. Actually, dozens of rows was returned
from the
database. However, when I tried to print out the
DataItem.ToString() using
Response.Write(), a NullReferenceException occured. But it works
fine, after
I had commented that line of code.
I don't know whether I wrote the code in the correct way, would
you please
point me out? Thanks
message
There is no difference where the code is.
Post the relevant fragment from the code and the .aspx file,
likely there
is a problem over there.
Eliyahu
Hi, all,
I was tangled by the DataGridItem.DataItem property. I tried
to invoke
that property to get and display the contents that was bound to
the
currently selected row. However, an exception surprised me that
it said
"Object reference not set to an instance of an object." How
could it
happen? I have set the data source, and called the DataBind().
I looked up the MSDN documents, and just find some
inessential
descriptions, and a code example. I didn't try that example by
myself,
but I noticed a difference that, the example uses the
single-file code
(i.e code was written in the .aspx file) while I wrote my code
in the
code-behind mode. So I wonder if this is the reason? But I'm
afraid I
would be puzzled if MS says the DataItem property will not be
available
through code-behind
Any help, please?
