Trouble with Listbox bind inside Gridview - asp.net

Question

I am a AS400 programmer asked to write a program in asp.net using vb.net. I have never done this before and I am having issues with populating a listbox in Gridview. I have researched this subject for days but all the code I have tried, found in examples, do not work. Please forgive any really bad code, with me being so new to .net, I am sure this could be written much better. I appreciate any help you may be able to offer. the grid is "AdjusterList" and the Listbox is called "MAICD". I think the 'failing/bad' code in
Public Sub AdjusterList_RowDataBound. It is giving me a null exception error the line before the databind; oCtrl.DataSource = oRs
I am using code given to me by a senior .net programmer, whom is not able to offer any more assistance to this newbie. Just Fyi....
Here is my aspx.
<div id="div1" runat="server">
<asp:GridView ID="AdjusterList" runat="server" Width="1100px"
ClientIDMode="Static" AllowSorting="True"
AutoGenerateColumns="False"
OnRowCommand="AdjusterList_RowCommand"
OnRowEditing="AdjusterList_RowEditing"
OnRowUpdating="AdjusterList_RowUpdating"
OnRowDeleting="AdjusterList_RowDeleting"
OnRowCancelingEdit="AdjusterList_RowCancelingEdit"
OnRowDataBound="AdjusterList_RowDataBound"
DataKeyNames="INSCD, INSSEQ"
ShowHeaderWhenEmpty="True" EditRowStyle-BackColor="#FF9900" PageSize="20"
EmptyDataText="NO RECORDS FOUND FOR THIS INSURER"
ShowFooter="True"EnableViewState="true">
<EditRowStyle BackColor="#FF9900" />
<RowStyle BackColor="White" ForeColor="Black" />
<Columns>
<asp:TemplateField>
<ItemTemplate>
<asp:LinkButton id="btnedit" runat="server" CommandName="Edit"/>
</ItemTemplate>
<EditItemTemplate>
<asp:LinkButton id="btnupdate" runat="server" CommandName="Update" Text="Save" />
<asp:LinkButton id="btncancel" runat="server" CommandName="Cancel" Text=Cancel"/>
</EditItemTemplate>
<FooterTemplate>
<asp:LinkButton id="btninsert" runat="server" CommandName="Insert" Text="Insert"/>
</FooterTemplate>
</asp:TemplateField>
<asp:TemplateField HeaderText ="Mail Code" ItemStyle-HorizontalAlign="Center">
<ItemTemplate>
<asp:Label ID="lblmaicd" runat="server" Text='<%# Bind("MAICD")%>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:ListBox ID="MAICD" runat="server" Rows="1"DataTextField="Text"
DataValueField='<%# Bind("MAICD")%></asp:ListBox>
</EditItemTemplate>
<FooterTemplate>
<asp:ListBox ID="MAICD" runat="server" width="200" DataTextField="Text">
</asp:ListBox>
</FooterTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
My code behind...
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.OleDb
Public Class EditAdjusterData
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e AsSystem.EventArgs)
Dim sAdjuster As String = Session("Adjuster")
Dim sSeqNo As String = Session("SeqNo")
PopulateEdit(sAdjuster, sSeqNo, dateok)
If IsPostBack Then
'divEdit.Visible = False
'divSelect.Visible = True
'ShowForm()
Else
AdjusterList.DataBind()
'divEdit.Visible = True
'divSelect.Visible = False
End If
End Sub
Protected Sub PopulateEdit(sValue As String, sValue2 As String, sValue3 As String)
' CALL TO PGRTSTLIB FILE INSP TO GET INSURER NAME
' 2ND CALL TO PGRTSTLIB FILE INSD
Dim oConn As New OleDbConnection()
Dim sConn As String = ""
Dim oCmd As New OleDbCommand()
Dim oAdapter As New OleDbDataAdapter()
Dim oRs As DataSet = New DataSet
Dim sSql As String = ""
sConn = "Provider=IBMDA400.DataSource.1;
oConn = New OleDb.OleDbConnection(sConn)
oConn.Open()
sSql = "SELECT INSCD, INSSEQ, MAICD, MAISEQ, (substr(char(EFFDT),5,2) || '-' || substr(char(EFFDT),7,2) || '-' || substr(char(EFFDT),1,4)) AS EFFDT, (substr(char(CANDT),5,2) || '-' || substr(char(CANDT),7,2) || '-' || substr(char(CANDT),1,4)) AS CANDT, ACCFIL FROM PGRTSTLIB.INSD WHERE INSCD = '" & sValue & "' "
oCmd = New OleDbCommand(sSql, oConn)
Session(INSCD) = INSCD
Session(EFFDT) = EFFDT
Session(MAICD) = MAICD
Session("CANDT") = CANDT
oCmd.CommandType = CommandType.Text
oAdapter.SelectCommand = oCmd
oAdapter.Fill(oRs, "Data")
Dim sMailCode As String = " "
Dim sMailSeq As String = " "
Dim pRow As DataRow
For Each pRow In oRs.Tables("Data").Rows
sMailCode = pRow("MAICD").ToString()
Next
Session(sMailCode) = MAICD
Session(MAICD) = sMailCode
Session(sMailCode) = sMailCode
AdjusterList.DataSource = oRs
'AdjusterList.DataBind()
'If sMailCode <> " " Then
' PopulateMailCode(sMailCode)
'End If
oRs.Dispose()
oAdapter.Dispose()
oCmd.Dispose()
oConn.Dispose()
End Sub
Protected Sub AdjusterList_PageIndexChanging(ByVal sender As Object,
ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs)
AdjusterList.PageIndex = e.NewPageIndex
AdjusterList.DataBind()
End Sub
Protected Sub AdjusterList_RowCommand(ByVal sender As Object,
ByVal e As System.Web.UI.WebControls.GridViewCommandEventArgs)
End Sub
Protected Sub AdjusterList_RowCreated(ByVal sender As Object,
ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs)
End Sub
Public Sub AdjusterList_RowDataBound(ByVal Sender As Object,
ByVal e As GridViewRowEventArgs) Handles AdjusterList.RowDataBound
If e.Row.RowType = DataControlRowType.DataRow Then
If e.Row.FindControl("MAICD") IsNot Nothing Then
Dim MAICD As ListBox = e.Row.FindControl("MAICD")
'If (e.Row.RowState And DataControlRowState.Edit) > 0 Then
BindAjusterList()
End If
End If
End Sub
Public Sub BindAjusterList()
Dim oConn As New OleDbConnection()
Dim sConn As String = ""
Dim oCmd As New OleDbCommand()
Dim oAdapter As New OleDbDataAdapter()
Dim oRs As DataSet = New DataSet
Dim sSql As String = ""
sConn = "Provider=IBMDA400.DataSource.1; "
oConn = New OleDb.OleDbConnection(sConn)
oConn.Open()
'sSql = "SELECT MAICD as Value, MAICD AS Text from PGRTSTLIB.INSM order by MAICD"
sSql = "SELECT MAICD As Value, MAICD AS TEXT from PGRTSTLIB.INSM"
oCmd = New OleDbCommand(sSql, oConn)
'oCmd.Parameters.Add(New SqlParameter("#Type", Insurer))
oCmd.CommandType = CommandType.Text
oAdapter.SelectCommand = oCmd
oAdapter.Fill(oRs, "ListBox")
Dim oCtrl As ListBox
oCtrl = AdjusterList.FindControl("MAICD")
oCtrl.Items.Add(New ListItem("", ""))
oCtrl.DataSource = oRs
oCtrl.DataBind()
oCtrl.Items.Insert(0, New ListItem(String.Empty, String.Empty))
If Len(sValue) > 0 Then
oCtrl.SelectedValue = sValue
Else
sValue = " "
End If
oRs.Dispose()
oAdapter.Dispose()
oCmd.Dispose()
oConn.Dispose()
End Sub
Public Sub AdjusterList_RowEditing(ByVal sender As Object,
ByVal e As System.Web.UI.WebControls.GridViewEditEventArgs)
AdjusterList.EditIndex = e.NewEditIndex
AdjusterList.DataBind()
End Sub
Protected Sub AdjusterList_RowUpdating(ByVal sender As Object,
ByVal e As System.Web.UI.WebControls.GridViewUpdateEventArgs)
' Dim row As GridViewRow = DirectCast(SubsidaryList.Rows(e.RowIndex), GridViewRow)
Dim INSCD As String = DirectCast(AdjusterList.Rows(e.RowIndex).Cells (0).FindControl ("INSCD"), TextBox).Text
Dim INSSEQ As String = DirectCast(AdjusterList.Rows(e.RowIndex).Cells(1).FindControl("INSSEQ"), TextBox).Text
Dim MAICD As String = DirectCast(AdjusterList.Rows(e.RowIndex).Cells(2).FindControl("MAICD"), ListBox).Text
Dim MAISEQ As String = DirectCast(AdjusterList.Rows(e.RowIndex).Cells(3).FindControl("MAISEQ"), TextBox).Text
Dim EFFDT As String = DirectCast(AdjusterList.Rows(e.RowIndex).Cells(4).FindControl("EFFDT"), TextBox).Text
Dim CANDT As String = DirectCast(AdjusterList.Rows(e.RowIndex).Cells(5).FindControl("CANDT"), TextBox).Text
Dim ACCFIL As String = DirectCast(AdjusterList.Rows(e.RowIndex).Cells(6).FindControl("ACCFIL"), TextBox).Text
AdjusterList.EditIndex = -1
AdjusterList.DataBind()
' New Data to DataBind to sql datasource and resend page after RECORD updated
Response.Redirect("EditAdjusterData.aspx")
End Sub
Protected Sub AdjusterList_RowCancelingEdit() Handles AdjusterList.RowCancelingEdit
AdjusterList.EditIndex = -1
AdjusterList.DataBind()
End Sub
End Class
I am so new to .net and I may not fully understand every example. I think the senior .net programmers think it is funny : (
Thanks so much and please feel free to contact me with any help you may be able to offer. I just need the darn listbox to populate. I removed any code I considered unrelated to this listbox issue.

Answer 1

In your markup, you should change the DataValueField property of your ListBox to the "Value" string, because it's the alias you are giving to the property in the query ("SELECT MAICD As Value, MAICD AS TEXT from PGRTSTLIB.INSM"):
<asp:ListBox ID="MAICD" runat="server" Rows="1"DataTextField="Text" DataValueField="Value"></asp:ListBox>
Also, in RowDataBound event, you are retrieving the ListBox instance for that row using the FindControl method, but then you are retrieving it again in the BindAjusterList() method. Try changing the method to receive the control found:
Public Sub AdjusterList_RowDataBound(ByVal Sender As Object, ByVal e As GridViewRowEventArgs) Handles AdjusterList.RowDataBound
If e.Row.RowType = DataControlRowType.DataRow Then
If e.Row.FindControl("MAICD") IsNot Nothing Then
Dim MAICD As ListBox = e.Row.FindControl("MAICD")
BindAjusterList(MAICD)
End If
End If
End Sub
Public Sub BindAjusterList(ByVal oCtrl As ListBox)
' existing logic
oCtrl.Items.Add(New ListItem("", ""))
oCtrl.DataSource = oRs
oCtrl.DataBind()
' existing logic
End Sub