value member into listbox

"dennist" <dennist@.zahav.nety.il> wrote
> Dim cmd As New OleDbCommand(strSQL, cn)
> Dim rdr As OleDbDataReader = cmd.ExecuteReader()
> While rdr.Read()
> 'lstCustomers.Items.Add(rdr(1))
>
Dennist,
Try the following:
lstCustomers.Items.Add(rdr.GetString(1))
--
Thanks,
Carl Prothman
Microsoft ASP.NET MVP
http://www.able-consulting.com
Thanks, carl,
that is superior coding in getting the first column into
the displaymember, but doesn't help me get the 0th column
into the valuemember.
dennist
>--Original Message--
>"dennist" <dennist@.zahav.nety.il> wrote
>> Dim cmd As New OleDbCommand(strSQL, cn)
>> Dim rdr As OleDbDataReader = cmd.ExecuteReader
()
>> While rdr.Read()
>> 'lstCustomers.Items.Add(rdr(1))
>Dennist,
>Try the following:
> lstCustomers.Items.Add(rdr.GetString(1))
>--
>Thanks,
>Carl Prothman
>Microsoft ASP.NET MVP
>http://www.able-consulting.com
>
>
>.
>
"dennist" <dennist@.zahav.net.il> wrote in message news:011801c35de0$303df490$a501280a@.phx.gbl...
> Thanks, carl,
> that is superior coding in getting the first column into
> the displaymember, but doesn't help me get the 0th column
> into the value member.
>
Dennist,
Do you mean like this?
lstCustomers.Items.Add(rdr.GetString(0) & " - " & rdr.GetString(1))
--
Thanks,
Carl Prothman
Microsoft ASP.NET MVP
http://www.able-consulting.com
dennist
Using ValueMember/DisplayMember is only relevant when you filling the list
with objects that contain more that one property (eg a DataTable with
columns or an object with properties)
Create a simple class with 2 properties (say ID and Name)
When reading the data, create a new instance and set its properties and then
add this instance to the listbox
myListBox.ValueMember = "ID"
myListBox.DisplayMember = "Name"
Do While rdr.Read
Dim obj as New myObj
With obj
.ID = rdr.GetInt32(0) 'assumes its an integer!
.Name = rdr.GetString(1)
End With
myListBox.Items.Add(obj)
Loop
SelectedItem will return myObj
SelectedValue will return myObj.ID
Stephen
"dennist" <dennist@.zahav.nety.il> wrote in message
news:0b7f01c35dd1$fdcb6820$a601280a@.phx.gbl...
> I finally figured out what others were telling me and was
> able to fill as list box with the following code:
> Imports System.Data
> Imports System.Data.OleDb
>
> Public Class Form1
>
> Inherits System.Windows.Forms.Form
>
> #Region " Windows Form Designer generated code "
> Public Sub New()
> MyBase.New()
> 'This call is required by the Windows Form
> Designer.
> InitializeComponent()
> 'Add any initialization after the
> InitializeComponent() call
> End Sub
> 'Form overrides dispose to clean up the component
> list.
> Protected Overloads Overrides Sub Dispose(ByVal
> disposing As Boolean)
> If disposing Then
> If Not (components Is Nothing) Then
> components.Dispose()
> End If
> End If
> MyBase.Dispose(disposing)
> End Sub
> 'Required by the Windows Form Designer
> Private components As System.ComponentModel.IContainer
> 'NOTE: The following procedure is required by the
> Windows Form Designer
> 'It can be modified using the Windows Form Designer.
> 'Do not modify it using the code editor.
> Friend WithEvents lstCustomers As
> System.Windows.Forms.ListBox
> <System.Diagnostics.DebuggerStepThrough()> Private
> Sub InitializeComponent()
> Me.lstCustomers = New System.Windows.Forms.ListBox
> Me.SuspendLayout()
> '
> 'lstCustomers
> '
> Me.lstCustomers.Location = New
> System.Drawing.Point(8, 16)
> Me.lstCustomers.Name = "lstCustomers"
> Me.lstCustomers.Size = New System.Drawing.Size
> (120, 147)
> Me.lstCustomers.TabIndex = 0
> '
> 'Form1
> '
> Me.AutoScaleBaseSize = New System.Drawing.Size(5,
> 13)
> Me.ClientSize = New System.Drawing.Size(292, 266)
> Me.Controls.Add(Me.lstCustomers)
> Me.Name = "Form1"
> Me.Text = "Form1"
> Me.ResumeLayout(False)
> End Sub
> #End Region
>
> Private Sub Form1_Load(ByVal sender As System.Object,
> ByVal e As System.EventArgs) Handles MyBase.Load
> Dim strConn, strSQL As String
> strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data
> Source=H:\Program Files\Microsoft Office\Office10
> \Samples\Northwind.mdb;" ' & "Admin" & ""
> strSQL = "SELECT CustomerID, CompanyName FROM
> Customers"
> Dim cn As New OleDbConnection(strConn)
> cn.Open()
> Dim cmd As New OleDbCommand(strSQL, cn)
> Dim rdr As OleDbDataReader = cmd.ExecuteReader()
> While rdr.Read()
> 'lstCustomers.Items.Add(rdr(1))
> 'MsgBox(rdr("CustomerID") & " - " & rdr
> ("CompanyName"))
> 'Console.WriteLine(rdr("CustomerID") & " - "
> & rdr("CompanyName"))
> End While
> rdr.Close()
> cn.Close()
> End Sub
> End Class
>
> The problem remaining is how do I get rdr(0) into the
> valuemember. This would really make me feel I'm getting
> somewhere.
> dennist
Stephen, you helped me get part way there, but..
Here are the changes in my code I made according to your
suggestions:
Dim cls1 As New Class1
While rdr.Read()
With cls1
.CustomerID = rdr.GetString(0)
.CustomerName = rdr.GetString(1)
End With
lstCustomers.Items.Add(cls1)
End While
rdr.Close()
cn.Close()
End Sub
Private Sub lstCustomers_SelectedIndexChanged(ByVal
sender As Object, ByVal e As System.EventArgs) Handles
lstCustomers.SelectedIndexChanged
MsgBox("CustomerID = " &
lstCustomers.SelectedValue)
End Sub
End Class
and here is the class
Public Class Class1
Private mCustomerID As String
Private mCustomerName As String
Public Property CustomerID() As String
Get
Return mCustomerID
End Get
Set(ByVal Value As String)
mCustomerID = Value
End Set
End Property
Public Property CustomerName() As String
Get
Return mCustomerName
End Get
Set(ByVal Value As String)
mCustomerName = Value
End Set
End Property
End Class
It works insofar as getting the names into the listbox,
as before. But I can't access the values, if any, and it
looks like they are empty.
if the selectedindexchanged event handler is
Private Sub lstCustomers_SelectedIndexChanged(ByVal
sender As Object, ByVal e As System.EventArgs) Handles
lstCustomers.SelectedIndexChanged
MsgBox("CustomerID = " &
lstCustomers.SelectedItem)
End Sub
I get this error message
An unhandled exception of
type 'System.InvalidCastException' occurred in
microsoft.visualbasic.dll
Additional information: Cast from type 'Class1' to
type 'String' is not valid.
if the event handler is:
Private Sub lstCustomers_SelectedIndexChanged(ByVal
sender As Object, ByVal e As System.EventArgs) Handles
lstCustomers.SelectedIndexChanged
MsgBox("CustomerID = " &
lstCustomers.SelectedValue)
End Sub
Then the message box comes up saying CustomerID =
and no value. In this case, being the northwind
database, the customer id is also a string.
How do I find out if the value is really in there, and
how do I access it. Why would it be blank?
Perhaps you have another way altogether of getting - in
simple code - values into a list box from a table in a
database. It was certainly easy enough in ADO without
contortions.
dennist
No, that doesn't work. I want a way to get the
customerID - which is also a string, since this is the
northwind database, into the value member.
dennist
>--Original Message--
>"dennist" <dennist@.zahav.net.il> wrote in message
news:011801c35de0$303df490$a501280a@.phx.gbl...
>> Thanks, carl,
>> that is superior coding in getting the first column
into
>> the displaymember, but doesn't help me get the 0th
column
>> into the value member.
>Dennist,
>Do you mean like this?
> lstCustomers.Items.Add(rdr.GetString(0) & " - " &
rdr.GetString(1))
>--
>Thanks,
>Carl Prothman
>Microsoft ASP.NET MVP
>http://www.able-consulting.com
>
>
>.
>
"dennist" <dennist@.zahav.net.il> wrote
> No, that doesn't work. I want a way to get the
> customerID - which is also a string, since this is the
> northwind database, into the value member.
>
Oh, you mean the ListBox's ValueMember property.
You can only specify the contents of the ValueMember property in cases
where you **bind data** to the ListBox.
Plus for Windows Applications, you can't bind a DataReader to a ListBox!
You must an object that implements the IList interface, such as a DataSet
or an Array.
e.g.
' Create the connection and sql strings
Dim connString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\nwind40.mdb;"
Dim sqlString As String = "SELECT CustomerID, CompanyName FROM Customers"
' Create a new connection, command and data adapter
Dim oledbConn As OleDbConnection = New OleDbConnection(connString)
Dim oledbCmd As OleDbCommand = New OleDbCommand(sqlString, oledbConn)
Dim oledbDataAdapter As OleDbDataAdapter = New OleDbDataAdapter
oledbDataAdapter.SelectCommand = oledbCmd
' Fill the DataSet
Dim customerDataSet As DataSet = New DataSet
oledbDataAdapter.Fill(customerDataSet, "Customers")
' Bind the DataSet to the DataList
ListBox1.ValueMember = customerDataSet.Tables("Customers").Columns(0).ColumnName
ListBox1.DisplayMember = customerDataSet.Tables("Customers").Columns(1).ColumnName
ListBox1.DataSource = customerDataSet.Tables("Customers")
--
Thanks,
Carl Prothman
Microsoft ASP.NET MVP
http://www.able-consulting.com
"dennist" <dennist@.zahav.net.il> wrote
> Since then, I've managed to put most of the logic in a
> module as a generic listbox filler. I have a global
> connect string, and send to the module sub FillListBox
> the listbox name by reference, the strSQL byval, and the
> table name by val.
> Is there any way I could overload the sub so it could
> accept either a listbox or a combobox?
>
Sure, just create another sub with the same name, but have it
accept a combobox parameter.
With VB.NET, you'll need to the use the Overloads keyword.
http://msdn.microsoft.com/library/en-us/vblr7/html/vastmsub.asp
Then each sub will call your common data access code and fill
the corresponding control that was pass in.
--
Thanks,
Carl Prothman
Microsoft ASP.NET MVP
http://www.able-consulting.com