I am going to past a dataset from First.aspx to Second.aspx.
A whole table will be displayed on First.aspx and partial columns
will be displayed on Second.aspx.
First.aspx view in browser works well if I exclude Second.aspx. But when Second.aspx is included in the project, an error happens.
I can't find what is wrong in my code. - System.NullReferenceException was unhandled by user code
-
Message="Object reference not set to an instance of an object."
First.aspx.cs - namespace FirstPage
-
{
-
public partial class GetStrings : System.Web.UI.Page
-
{
-
getStrings g = new getStrings();
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protected void Page_Load(object sender, EventArgs e)
-
{
-
string strConnectionString = ConfigurationManager.ConnectionStrings["SqlConnectionString"].ConnectionString;
-
SqlConnection myConnection = new SqlConnection(strConnectionString);
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DataSet myDataSet = new DataSet();
-
try
-
{
-
myConnection.Open();
-
// create the data
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GenerateDataSet(myDataSet, myConnection);
-
}
-
finally
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{
-
myConnection.Close();
-
// bind each to table to a grid
-
-
}
-
Session["myds"] = myDataSet;
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// databind the page
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GridView1.DataSource = myDataSet.Tables["Weather"];
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GridView1.DataBind();
-
}
and
Second.aspx.cs - using System;
-
using System.Data;
-
using System.Data.SqlClient;
-
using System.Configuration;
-
using System.Web;
-
using System.Web.Security;
-
using System.Web.UI;
-
using System.Web.UI.WebControls;
-
using System.Web.UI.WebControls.WebParts;
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using System.Web.UI.HtmlControls;
-
using FirstPage;
-
-
public partial class Second : System.Web.UI.Page
-
{
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protected void Page_Load(object sender, EventArgs e)
-
{
-
DataSet ds = (DataSet)Session["myds"];
-
FillTable(ds);
-
GridView1.DataSource = ds.Tables["Index"];
-
GridView1.DataBind();
-
}
-
-
void FillTable(DataSet dset)
-
{
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DataTable indexTable = dset.Tables.Add("Index");
-
-
DataColumn indexID =
-
indexTable.Columns.Add("State", typeof(string));
-
indexTable.Columns.Add("Division", typeof(string));
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indexTable.Columns.Add("MOIST_INDEX", typeof(string));
-
indexTable.Columns.Add("DROUGHT_INDEX", typeof(string));
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}
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}
Second.aspx - <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Second.aspx.cs" Inherits="Second" %>
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<%@ Import Namespace="System.Data" %>
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<%@ Import Namespace="System.Data.SqlClient" %>
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<%@ Reference Page="First.aspx" %>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
-
-
<html xmlns="http://www.w3.org/1999/xhtml">
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<head id="Head1" runat="server">
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<title>Untitled Page</title>
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</head>
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<body>
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<form id="form1" runat="server">
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<div>
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<asp:GridView ID="GridView1" runat="server">
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</asp:GridView>
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</div>
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</form>
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</body>
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</html>
Any help will be appreciated.
2  2989  
Second.aspx.cs
Code: ( text )
using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using FirstPage;
public partial class Second : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
DataSet ds = (DataSet)Session["myds"];
FillTable(ds);
GridView1.DataSource = ds.Tables["Index"];
GridView1.DataBind();
}
void FillTable(DataSet dset)
{
DataTable indexTable = dset.Tables.Add("Index");
DataColumn indexID =
indexTable.Columns.Add("State", typeof(string));
indexTable.Columns.Add("Division", typeof(string));
indexTable.Columns.Add("MOIST_INDEX", typeof(string));
indexTable.Columns.Add("DROUGHT_INDEX", typeof(string));
}
}
I believe what is happening is table Index does not exist in your dataset so GridView1.DataSource = ds.Tables["Index"];
is creating an object reference not set to an instance of an object error. There are a few ways to change your code to eliminate this error. Here a 2 options.
1. Change your parameter to include the out keyword - public void FillTable(out DataSet dset)
-
{
-
DataTable indexTable = dset.Tables.Add("Index");
-
-
DataColumn indexID =
-
indexTable.Columns.Add("State", typeof(string));
-
indexTable.Columns.Add("Division", typeof(string));
-
indexTable.Columns.Add("MOIST_INDEX", typeof(string));
-
indexTable.Columns.Add("DROUGHT_INDEX", typeof(string));
-
}
2. Change your method to return a DataSet and then add the DataTable to your DataSet. - public DataSet FillTable(DataSet dset)
-
{
-
DataTable indexTable = dset.Tables.Add("Index");
-
-
DataColumn indexID =
-
indexTable.Columns.Add("State", typeof(string));
-
indexTable.Columns.Add("Division", typeof(string));
-
indexTable.Columns.Add("MOIST_INDEX", typeof(string));
-
indexTable.Columns.Add("DROUGHT_INDEX", typeof(string));
-
-
return dset;
-
}
-
protected void Page_Load(object sender, EventArgs e)
-
{
-
DataSet ds = (DataSet)Session["myds"];
-
ds = FillTable(ds);
-
GridView1.DataSource = ds.Tables["Index"];
-
GridView1.DataBind();
-
}
-
Nathan
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