Adding to a list box in ASP .Net

[Paul M.]

Hi,
I am trying to add a dataset to a list box on an asp .net page, the
query results in about 20 rows coming back when I run it in access but when
I loop through the dataset adding each records field to the list box, the
list box only shows the first one and no others. Anyone know whats going on?

Thanks
Paul

Code ======================================

Imports System.Diagnostics

Public Class WebForm1

Inherits System.Web.UI.Page

Protected WithEvents lstModName As System.Web.UI.WebControls.ListBox

Const MODULENAME = "frmFilter.aspx.vb"

#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

1: Dim conMain As New System.Data.OleDb.OleDbConnection()

2: Dim comMain As New System.Data.OleDb.OleDbCommand()

3: Dim rsData As System.Data.OleDb.OleDbDataReader

4: On Error GoTo ERRORHANDLER

10: conMain.ConnectionString = ("Provider=Microsoft.Jet.OLEDB.4.0; Data
Source=D:\GizmosDB.mdb;")

20: conMain.Open()

30: comMain.CommandText = "SELECT DISTINCT tblGizmos.[ModName] FROM
tblGizmos;"

40: comMain.CommandType = CommandType.Text

50: comMain.Connection = (conMain)

60: rsData = comMain.ExecuteReader(CommandBehavior.SingleRow)

70: While rsData.Read()

80: lstModName.Items.Add(rsData("ModName").ToString)

90: End While

100: rsData.Close()

End Sub

End Class

 

[Harsh Thakur]

Hi Paul,

Well, the following line of code could be the culprit:

60: rsData = comMain.ExecuteReader(CommandBehavior.SingleRow)

Try placing it inside the while loop.

Secondly, why aren't you using a DataSet and a DataAdapter?

Hi,
I am trying to add a dataset to a list box on an asp .net page, the
query results in about 20 rows coming back when I run it in access but when
I loop through the dataset adding each records field to the list box, the
list box only shows the first one and no others. Anyone know whats going on?

Thanks
Paul

Code ======================================

Imports System.Diagnostics

Public Class WebForm1

Inherits System.Web.UI.Page

Protected WithEvents lstModName As System.Web.UI.WebControls.ListBox

Const MODULENAME = "frmFilter.aspx.vb"

#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

1: Dim conMain As New System.Data.OleDb.OleDbConnection()

2: Dim comMain As New System.Data.OleDb.OleDbCommand()

3: Dim rsData As System.Data.OleDb.OleDbDataReader

4: On Error GoTo ERRORHANDLER

10: conMain.ConnectionString = ("Provider=Microsoft.Jet.OLEDB.4.0; Data
Source=D:\GizmosDB.mdb;")

20: conMain.Open()

30: comMain.CommandText = "SELECT DISTINCT tblGizmos.[ModName] FROM
tblGizmos;"

40: comMain.CommandType = CommandType.Text

50: comMain.Connection = (conMain)

60: rsData = comMain.ExecuteReader(CommandBehavior.SingleRow)

70: While rsData.Read()

80: lstModName.Items.Add(rsData("ModName").ToString)

90: End While

100: rsData.Close()

End Sub

End Class

 

[James Zhuo]

To Paul:

I think it's just your loop structure, i am not sure if that is the correct
while loop construct
I think the while loop should be something like
Do While ds.Read()
lstModName.Items.Add(rsData("ModName").ToString)
Loop
I see nothing else wrong with wat you did


To Harsh:
All he wanted to do is to fill up a list, datareader may in fact be faster
in this situation

Cheers

J

ps: i am no expert

 

[Iain Paton]

I am trying to add a dataset to a list box on an asp .net page, the
query results in about 20 rows coming back when I run it in access but when
I loop through the dataset adding each records field to the list box, the
list box only shows the first one and no others. Anyone know whats going

on?

Yes, you're not reading the docs.

60: rsData = comMain.ExecuteReader(CommandBehavior.SingleRow)

What does this line do ? Specifically CommandBehaviour.SingleRow ?
How do you think that might relate to your problem ?

The answer is here (sorry if the url wraps)
http://msdn.microsoft.com/library/en-us/cpref/html/frlrfSystemDataCommandBeh
aviorClassTopic.asp

I
--

 

[Paul M.]

Bingo, changing:

60: rsData = comMain.ExecuteReader(CommandBehavior.SingleRow)

to

60: rsData = comMain.ExecuteReader(CommandBehavior.SingleResult)

solves the problem.

Thanks to those who pointed it out!

Cheers
Paul M.

 

[peruser]

Paul - The problem is indeed the loop syntax. Please see:
http://msdn.microsoft.com/library/d.../vbcon98/html/vbconpart1visualbasicbasics.asp

At the bottom you will see the following suggestion:
While...Wend loops can be nested to any level. Each Wend matches the most
recent While.

Tip The Do...Loop statement provides a more structured and flexible way to
perform looping.

There is no 'End While' in Visual Basic, and a search of MSDN returned no
results for 'End While'.

 

[Paul M.]

Hello,
thanks for replying, I tried the loop syntax link you suggested
however it was invalid. As for your point about "end while" this is legal
syntax for vb .net, are you using an old version of MSDN?

Thanks
Paul M.

Paul - The problem is indeed the loop syntax. Please see:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcon98/htm
l/vbconpart1visualbasicbasics.asp

At the bottom you will see the following suggestion:
While...Wend loops can be nested to any level. Each Wend matches the most
recent While.

Tip The Do...Loop statement provides a more structured and flexible way to
perform looping.

There is no 'End While' in Visual Basic, and a search of MSDN returned no
results for 'End While'.

Hi,
I am trying to add a dataset to a list box on an asp .net page, the
query results in about 20 rows coming back when I run it in access but when
I loop through the dataset adding each records field to the list box, the
list box only shows the first one and no others. Anyone know whats going on?

Thanks
Paul

Code ======================================

Imports System.Diagnostics

Public Class WebForm1

Inherits System.Web.UI.Page

Protected WithEvents lstModName As System.Web.UI.WebControls.ListBox

Const MODULENAME = "frmFilter.aspx.vb"

#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

1: Dim conMain As New System.Data.OleDb.OleDbConnection()

2: Dim comMain As New System.Data.OleDb.OleDbCommand()

3: Dim rsData As System.Data.OleDb.OleDbDataReader

4: On Error GoTo ERRORHANDLER

10: conMain.ConnectionString = ("Provider=Microsoft.Jet.OLEDB.4.0; Data
Source=D:\GizmosDB.mdb;")

20: conMain.Open()

30: comMain.CommandText = "SELECT DISTINCT tblGizmos.[ModName] FROM
tblGizmos;"

40: comMain.CommandType = CommandType.Text

50: comMain.Connection = (conMain)

60: rsData = comMain.ExecuteReader(CommandBehavior.SingleRow)

70: While rsData.Read()

80: lstModName.Items.Add(rsData("ModName").ToString)

90: End While

100: rsData.Close()

End Sub

End Class