p2p.wrox.com: Archives - aspx

aspx_beginners thread: Codebehind page

Message #1 by "Datatal AB - Gauffin, Jonas" <Jonas@d...> on Fri, 26 Apr 2002 08:56:59 +0200

Hi folks

Im trying to create a codebehind page, but I get this error:

System.NullReferenceException: Object reference not set to an instance 
of an object.
Line 39:         Dim dt As DataTable =3D ds.Tables(0)
Line 40:
Line 41:         mList.DataSource =3D dt                  <---- this 
line
Line 42:         mList.DataBind()
Line 43:


aspx:
<%@ Page Language=3D"vb" CodeBehind=3D"Test.vb" Inherits=3D"Test" 
Src=3D"Test.vb" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
	<head>
		<title>WebForm1</title>
		<meta name=3D"GENERATOR" content=3D"Microsoft Visual Studio.NET 7.0">
		<meta name=3D"CODE_LANGUAGE" content=3D"Visual Basic 7.0">
		<meta name=3D"vs_defaultClientScript" content=3D"JavaScript">
		<meta name=3D"vs_targetSchema" 
content=3D"http://schemas.microsoft.com/intellisense/ie5">
	</head>
	<body MS_POSITIONING=3D"GridLayout">
	 <form action=3D"WebForm1.aspx" method=3D"post" runat=3D"server" 
ID=3D"Form1">

		<asp:DataGrid ID=3D"mList">
			<Columns>
				<asp:BoundColumn DataField=3D"name"></asp:BoundColumn>
				<asp:BoundColumn DataField=3D"caseid"></asp:BoundColumn>
			</Columns>
		</asp:DataGrid>
	</form>
	</body>
</html>

vb:
Imports Microsoft.Data.Odbc
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.HtmlControls
Imports System.Data

Public Class WebForm1
    Inherits System.Web.UI.Page

    Public mList As System.Web.UI.WebControls.DataGrid

#Region " Web Form Designer Generated Code "

    'This call is required by the Web Form Designer.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub 
InitializeComponent()

    End Sub

    Private Sub Page_Init(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Init
        'CODEGEN: This method call is required by the Web Form Designer
        'Do not modify it using the code editor.
        InitializeComponent()
    End Sub

#End Region

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As 
System.EventArgs) Handles MyBase.Load
        'Put user code to initialize the page here
        Dim cmd As OdbcCommand
        Dim sql As String =3D "SELECT name,caseid FROM case_info"
        Dim conStr As String =3D 
"driver=3D{MySQL};server=3Dsql3;uid=3Droot;database=3Dsupport3;OPTION=3D1
7923"

        Dim da As OdbcDataAdapter =3D New OdbcDataAdapter(sql, conStr)
        Dim ds As New DataSet()

        da.Fill(ds, "case_info")
        'dim bldr as

        Dim dt As DataTable =3D ds.Tables(0)

        mList.DataSource =3D dt
        mList.DataBind()


    End Sub

End Class

Message #2 by "Minh T. Nguyen" <nguyentriminh@y...> on Fri, 26 Apr 2002 08:47:21 -0700

Hi,

	Probably your <asp:DataGrid ID="mList"> tag is missing the
runat="server" attribute.

Later,
Minh.

-----Original Message-----
From: Datatal AB - Gauffin, Jonas [mailto:Jonas@d...] 
Sent: Thursday, April 25, 2002 11:57 PM
To: aspx_beginners
Subject: [aspx_beginners] Codebehind page


Hi folks

Im trying to create a codebehind page, but I get this error:

System.NullReferenceException: Object reference not set to an instance
of an object.
Line 39:         Dim dt As DataTable = ds.Tables(0)
Line 40: 
Line 41:         mList.DataSource = dt                  <---- this line
Line 42:         mList.DataBind()
Line 43: 
 

aspx:
<%@ Page Language="vb" CodeBehind="Test.vb" Inherits="Test"
Src="Test.vb" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
	<head>
		<title>WebForm1</title>
		<meta name="GENERATOR" content="Microsoft Visual
Studio.NET 7.0">
		<meta name="CODE_LANGUAGE" content="Visual Basic 7.0">
		<meta name="vs_defaultClientScript"
content="JavaScript">
		<meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5">
	</head>
	<body MS_POSITIONING="GridLayout">
	 <form action="WebForm1.aspx" method="post" runat="server"
ID="Form1">

		<asp:DataGrid ID="mList">
			<Columns>
				<asp:BoundColumn
DataField="name"></asp:BoundColumn>
				<asp:BoundColumn
DataField="caseid"></asp:BoundColumn>
			</Columns>
		</asp:DataGrid>
	</form>
	</body>
</html>

vb:
Imports Microsoft.Data.Odbc
Imports System.Web.UI
Imports System.Web.UI.WebControls
Imports System.Web.UI.HtmlControls
Imports System.Data

Public Class WebForm1
    Inherits System.Web.UI.Page

    Public mList As System.Web.UI.WebControls.DataGrid

#Region " Web Form Designer Generated Code "

    'This call is required by the Web Form Designer.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub
InitializeComponent()

    End Sub

    Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Init
        'CODEGEN: This method call is required by the Web Form Designer
        'Do not modify it using the code editor.
        InitializeComponent()
    End Sub

#End Region

    Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles MyBase.Load
        'Put user code to initialize the page here
        Dim cmd As OdbcCommand
        Dim sql As String = "SELECT name,caseid FROM case_info"
        Dim conStr As String 
"driver={MySQL};server=sql3;uid=root;database=support3;OPTION=17923"

        Dim da As OdbcDataAdapter = New OdbcDataAdapter(sql, conStr)
        Dim ds As New DataSet()

        da.Fill(ds, "case_info")
        'dim bldr as 

        Dim dt As DataTable = ds.Tables(0)

        mList.DataSource = dt
        mList.DataBind()


    End Sub

End Class

Message #3 by "Datatal AB - Gauffin, Jonas" <Jonas@d...> on Mon, 29 Apr 2002 09:14:00 +0200

lol. thanks! =3D)

> -----Original Message-----
> From: Minh T. Nguyen [mailto:nguyentriminh@y...]
> Sent: den 26 april 2002 17:47
> To: aspx_beginners
> Subject: [aspx_beginners] RE: Codebehind page
>
>
> Hi,
>
> 	Probably your <asp:DataGrid ID=3D"mList"> tag is missing the
> runat=3D"server" attribute.
>
> Later,
> Minh.
>
> -----Original Message-----
> From: Datatal AB - Gauffin, Jonas [mailto:Jonas@d...]
> Sent: Thursday, April 25, 2002 11:57 PM
> To: aspx_beginners
> Subject: [aspx_beginners] Codebehind page
>
>
> Hi folks
>
> Im trying to create a codebehind page, but I get this error:
>
> System.NullReferenceException: Object reference not set to an instance
> of an object.
> Line 39:         Dim dt As DataTable =3D ds.Tables(0)
> Line 40:
> Line 41:         mList.DataSource =3D dt                  <----
> this line
> Line 42:         mList.DataBind()
> Line 43:
> 
>
> aspx:
> <%@ Page Language=3D"vb" CodeBehind=3D"Test.vb" Inherits=3D"Test"
> Src=3D"Test.vb" %>
> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
> <html>
> 	<head>
> 		<title>WebForm1</title>
> 		<meta name=3D"GENERATOR" content=3D"Microsoft Visual
> Studio.NET 7.0">
> 		<meta name=3D"CODE_LANGUAGE" content=3D"Visual Basic 7.0">
> 		<meta name=3D"vs_defaultClientScript"
> content=3D"JavaScript">
> 		<meta name=3D"vs_targetSchema"
> content=3D"http://schemas.microsoft.com/intellisense/ie5">
> 	</head>
> 	<body MS_POSITIONING=3D"GridLayout">
> 	 <form action=3D"WebForm1.aspx" method=3D"post" runat=3D"server"
> ID=3D"Form1">
>
> 		<asp:DataGrid ID=3D"mList">
> 			<Columns>
> 				<asp:BoundColumn
> DataField=3D"name"></asp:BoundColumn>
> 				<asp:BoundColumn
> DataField=3D"caseid"></asp:BoundColumn>
> 			</Columns>
> 		</asp:DataGrid>
> 	</form>
> 	</body>
> </html>
>
> vb:
> Imports Microsoft.Data.Odbc
> Imports System.Web.UI
> Imports System.Web.UI.WebControls
> Imports System.Web.UI.HtmlControls
> Imports System.Data
>
> Public Class WebForm1
>     Inherits System.Web.UI.Page
>
>     Public mList As System.Web.UI.WebControls.DataGrid
>
> #Region " Web Form Designer Generated Code "
>
>     'This call is required by the Web Form Designer.
>     <System.Diagnostics.DebuggerStepThrough()> Private Sub
> InitializeComponent()
>
>     End Sub
>
>     Private Sub Page_Init(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles MyBase.Init
>         'CODEGEN: This method call is required by the Web
> Form Designer
>         'Do not modify it using the code editor.
>         InitializeComponent()
>     End Sub
>
> #End Region
>
>     Private Sub Page_Load(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles MyBase.Load
>         'Put user code to initialize the page here
>         Dim cmd As OdbcCommand
>         Dim sql As String =3D "SELECT name,caseid FROM case_info"
>         Dim conStr As String =3D
> 
"driver=3D{MySQL};server=3Dsql3;uid=3Droot;database=3Dsupport3;OPTION=3D1
7923"
>
>         Dim da As OdbcDataAdapter =3D New OdbcDataAdapter(sql, conStr)
>         Dim ds As New DataSet()
>
>         da.Fill(ds, "case_info")
>         'dim bldr as
>
>         Dim dt As DataTable =3D ds.Tables(0)
>
>         mList.DataSource =3D dt
>         mList.DataBind()
>
>
>     End Sub
>
> End Class
>
>
>
>
>

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