DropDownList Issue

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DropDownList Issue

Hi All

I'm trying to learn ASP.Net (VB)

I'm having a question on a dropdown list. I have populated the list using a dataset ( a list of databases).

The dropdown list code

asp.net Code:

<asp:DropDownList ID="ddlDBs" runat="server" AutoPostBack="True" Width="192px">
        </asp:DropDownList><br />

The code to populate

vb.net Code:

Protected Sub getDatabaseNames()
        Dim oDA As SqlClient.SqlDataAdapter
        Dim oDS As DataSet = New DataSet
        Dim oCmd As SqlClient.SqlCommand = New SqlClient.SqlCommand
        Try
            Dim SQL As String = String.Empty
            SQL = "Select Name From sys.databases Where Name NOT IN ('master','msdb','model','tempdb') Order by Name"
 
            If Me.sqlConnection.State = ConnectionState.Closed Then
                Me.openConn()
            End If
            oDA = New SqlClient.SqlDataAdapter(SQL, Me.sqlConnection)
           
            oDA.Fill(oDS)
            Me.ddlDBs.DataSource = oDS.Tables(0).DefaultView
            Me.ddlDBs.DataTextField = "Name"
            Me.ddlDBs.DataBind()
            Me.ddlDBs.ClearSelection()
 
        Catch ex As Exception
            Me.lblMessages.Text = ex.Message
        Finally
            If oDS IsNot Nothing Then
                oDS.Dispose()
            End If
            If oCmd IsNot Nothing Then
                oCmd.Dispose()
            End If
        End Try
        If Me.sqlConnection.State = ConnectionState.Open Then
            Me.closeConn()
        End If
 
    End Sub

This part works. I get a list of databases in the list. My problem is when I make a selection from the list. I always get the first item in the list as selected not what I actually select.

Here is the code for the selected index change

vb.net Code:

Protected Sub ddlDBs_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ddlDBs.SelectedIndexChanged
        Response.Write("The database selected is: " & Me.ddlDBs.SelectedItem.Text & System.Environment.NewLine)
        'Response.Write("The database selected is: " & Me.ddlDBs.SelectedIndex)
    End Sub

Nov 14th, 2009, 02:49 PM
gep13

Re: DropDownList Issue

Hey,

Rather than use SelectedItem, try SelectedValue.

Also, I know it may seem "easy" to use Response.Write, I have found that it can actually confuse matters when it comes to debugging and layouts etc, so I would encourage you not to use it.

Rather write out to a Label Control, or simply do a Debug.Write to see it in the Output Window.

Hope that helps!!

Gary
Nov 14th, 2009, 03:00 PM
GaryMazzone

Re: DropDownList Issue

Tried Still always comes back to the first item in the list box. I can change the item. I see the item get selected but as soon as I let go of the mouse button the selection goes back to the first item.
Nov 15th, 2009, 04:33 AM
gep13

Re: DropDownList Issue

Hey,

Can you strip this down to the bare minimum and try the following:

Code:

Public Partial Class WebForm4 Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load DropDownList1.Items.Add("1") DropDownList1.Items.Add("2") DropDownList1.Items.Add("3") DropDownList1.Items.Add("4") DropDownList1.Items.Add("5") DropDownList1.Items.Add("6") End Sub Protected Sub DropDownList1_SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles DropDownList1.SelectedIndexChanged Label1.Text = DropDownList1.SelectedValue.ToString() End Sub End Class

Code:

<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="WebForm4.aspx.vb" Inherits="VBWebApplication.WebForm4" %> <!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" > <head runat="server"> <title></title> </head> <body> <form id="form1" runat="server"> <div> <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"> </asp:DropDownList> </div> <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label> </form> </body> </html>

This works exactly how I would expect it to.

Gary