I spent my whole day but I could not solve the problem. I dont have much experience in Asp.net. Please help... DropDownList dont send selected value to the Sub DropDown_SelectedIndexChanged
The Error Message is:Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.
Source Error:
Line 38: Protected WithEvents ItemDropDown As System.Web.UI.WebControls.DropDownList
Line 39: Sub DropDown_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
Line 40: Dim x As String= ItemDropDown.SelectedItem.Value
Line 41: label.Text= x
Line 42: End Sub
<%@ Page Language="VB" Debug="true" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<script language="VB" Debug="true" runat="server">
Sub Page_Load(Source As Object, E As EventArgs)
If Not IsPostBack Then
bindDataGrid
End If
End Sub
Sub bindDataGrid
Dim myConn As SqlConnection
Dim mySqlAdapter As SqlDataAdapter
Dim connStr, sqlStr As String
Dim myDataSet As New Dataset
connStr="server=SELIM; uid=xxxx; pwd=xxxx; Database=TestFiles"
sqlStr="SELECT * FROM TestFiles"
myConn= New SqlConnection(connStr)
myConn.Open()
mySqlAdapter=New SqlDataAdapter(sqlStr,myConn)
mySqlAdapter.Fill(myDataSet,"Sarkilar")
FileList.DataSource=myDataSet.Tables("Sarkilar")
FileList.DataBind()
myConn.Close()
End Sub
Protected WithEvents ItemDropDown As System.Web.UI.WebControls.DropDownList
Sub DropDown_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs)
Dim x As String= ItemDropDown.SelectedItem.Value
label.Text= x
End Sub
Sub doPaging(s As Object, e As DataGridPageChangedEventArgs)
FileList.CurrentPageIndex=e.NewPageIndex
bindDataGrid
End Sub
</script>
<html>
<body bgcolor="#E5F2D8">
<form runat="server">
<p><font face="Verdana" size="1" Color="#669933" ><center>
(Mozilla Kullanicilarinin dosyayi indirdikten sonra dosyanin uzantisinida mp3 olarak degistirmeleri gerekmektedir)
</center></font></p>
<asp:DataGrid id="FileList" runat="server"
BorderColor="Gray"
BorderWidth="2"
CellPadding="4"
ShowHeader="true"
Align="center"
AutoGenerateColumns="false"
AllowPaging="true" PageSize="10"
PagerStyle-Mode="NumericPages"
PagerStyle-HorizontalAlign="Center"
OnPageIndexChanged="doPaging"
>
<HeaderStyle BorderColor="white" BackColor="#669933"
ForeColor="White"
Font-Bold="True"
Font-Name="Arial"
Font-Size="9" HorizontalAlign="Center"/>
<Columns>
<asp:TemplateColumn HeaderText="Sarki Ismi">
<ItemTemplate>
<b>
<font face="arial" size="1" Color="#336633">
<%# DataBinder.Eval(Container.DataItem, "MyFileName") %>
</b>
</font>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="Dosya Uzantisi">
<ItemTemplate>
<b>
<font face="arial" size="1" Color="#336633">
<%# DataBinder.Eval(Container.DataItem, "FileType") %>
</b>
</font>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="Dosyayi Indir">
<ItemTemplate>
<b>
<font face="arial" size="1" Color="#336633">
<a href="indir.aspx?ID=<%# DataBinder.Eval(Container.DataItem, "ID") %>">
Indir</a>
</b>
</font>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="Puanlama">
<ItemTemplate>
<b>
<font face="arial" size="1" Color="#336633">
<%# DataBinder.Eval(Container.DataItem, "ID") %>
</b>
</font>
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="Oy Ver">
<ItemTemplate>
<asp:DropDownList ID="ItemDropDown" Runat="server"
AutoPostBack="True"
OnSelectedIndexChanged="DropDown_SelectedIndexChanged">
<asp:ListItem Selected="True" Text="Puan Ver"/>
<asp:ListItem Value="1" Text="1"/>
<asp:ListItem Value="2" Text="2"/>
<asp:ListItem Value="3" Text="3"/>
<asp:ListItem Value="4" Text="4"/>
<asp:ListItem Value="5" Text="5"/>
</asp:DropDownList>
</ItemTemplate>
</asp:TemplateColumn>
</Columns>
</asp:DataGrid>
</form>
<asp:label id="label" runat="server"/>
<body>
</html>
