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ASP.Net VB Update Gridview DirectCast Object reference not set to an instance of an object.

Hi Experts,
Receiving an error, "Object reference not set to an instance of an object.", when try to use result on the 2nd DirectCast.

Using vb & asp.net.
The strange thing is if I uncomment the rest of the DirectCast & from
'Using con
' Using cmd As New OleDbCommand(strSQL, con)
on down. The error happens and the database gets updated.

Here's the front page:
~~~~~~~~~~~~~~~~~~~~~~~~~

<asp:GridView ID="gvOrderDetails" runat="server" AutoGenerateColumns="False" 
     DataKeyNames="Order_Details_ID" 
     Width="745px" BorderWidth="1px"
     OnRowCancelingEdit="gvOrderDetails_RowCancelingEdit"
     OnRowDeleting="gvOrderDetails_RowDeleting" 
     OnRowEditing="gvOrderDetails_RowEditing" 
     OnRowUpdating="gvOrderDetails_RowUpdating">
     <Columns>
         <asp:TemplateField HeaderText="ID" SortExpression="Order_Details_ID" Visible="False">
             <ItemTemplate>
                 <asp:Label ID="lblID" runat="server" Text='<%# Bind("Order_Details_ID") %>'></asp:Label>
             </ItemTemplate>
         </asp:TemplateField>
         <asp:TemplateField HeaderText="Quantity" SortExpression="Quantity">
             <ItemTemplate>
                 <asp:Label ID="lblQty" runat="server" Text='<%# Bind("Quantity") %>'></asp:Label>
             </ItemTemplate>
             <EditItemTemplate>
                 <asp:TextBox ID="txtQty" runat="server" Text='<%# Bind("Quantity") %>'></asp:TextBox>
             </EditItemTemplate>
             <ControlStyle CssClass="text" Width="50px" />
             <HeaderStyle CssClass="textBold" Width="50px" />
             <ItemStyle CssClass="text" HorizontalAlign="Center" Width="50px" />
         </asp:TemplateField>
         <asp:TemplateField HeaderText="Product" SortExpression="Product_ID">
             <ItemTemplate>
                 <asp:Label ID="lblProd" runat="server" Text='<%# Bind("Product_ID") %>'></asp:Label>
             </ItemTemplate>
             <EditItemTemplate>
                 <asp:TextBox ID="txtProd" runat="server" Text='<%# Bind("Product_ID") %>'></asp:TextBox>
             </EditItemTemplate>
             <ControlStyle CssClass="text" Width="150px" />
             <HeaderStyle CssClass="textBold" Width="150px" />
             <ItemStyle CssClass="text" Width="150px" />
         </asp:TemplateField>
         <asp:TemplateField HeaderText="Year" SortExpression="Product_Year">
             <ItemTemplate>
                 <asp:Label ID="lblYear" runat="server" Text='<%# Bind("Product_Year") %>'></asp:Label>
             </ItemTemplate>
             <EditItemTemplate>
                 <asp:TextBox ID="txtYear" runat="server" Text='<%# Bind("Product_Year") %>'></asp:TextBox>
             </EditItemTemplate>
             <ControlStyle CssClass="text" Width="50px" />
             <HeaderStyle CssClass="textBold" />
             <ItemStyle CssClass="text" HorizontalAlign="Center" Width="50px" />
         </asp:TemplateField>
         <asp:TemplateField HeaderText="Unit Price" SortExpression="Price">
             <ItemTemplate>
                 <asp:Label ID="lblPrice" runat="server" Text='<%# Bind("Price", "{0:0.00}") %>'></asp:Label>
             </ItemTemplate>
             <EditItemTemplate>
                 <asp:TextBox ID="txtPrice" runat="server" 
                     Text='<%# Bind("Price", "{0:0.00}") %>'></asp:TextBox>
             </EditItemTemplate>
             <ControlStyle CssClass="text" Width="75px" />
             <HeaderStyle CssClass="textBold" />
             <ItemStyle CssClass="text" HorizontalAlign="Right" Width="75px" />
         </asp:TemplateField>
         <asp:TemplateField HeaderText="Item Cost" SortExpression="Item_Total">
             <ItemTemplate>
                 <asp:Label ID="lblCost" runat="server" 
                     Text='<%# Bind("Item_Total", "{0:0.00}") %>'></asp:Label>
             </ItemTemplate>
             <EditItemTemplate>
                 <asp:TextBox ID="txtCost" runat="server" 
                     Text='<%# Bind("Item_Total", "{0:0.00}") %>'></asp:TextBox>
             </EditItemTemplate>
             <ControlStyle CssClass="text" Width="100px" />
             <HeaderStyle CssClass="textBold" />
             <ItemStyle CssClass="text" HorizontalAlign="Right" Width="100px" />
         </asp:TemplateField>
         <asp:TemplateField HeaderText="Ship Date" SortExpression="Item_Shipped">
             <ItemTemplate>
                 <asp:Label ID="lblShip" runat="server" 
                     Text='<%# Bind("Item_Shipped", "{0:M/d/yyyy}") %>'></asp:Label>
             </ItemTemplate>
             <EditItemTemplate>
                 <asp:TextBox ID="txtShip" runat="server" 
                     Text='<%# Bind("Item_Shipped", "{0:M/d/yyyy}") %>'></asp:TextBox>
             </EditItemTemplate>
             <ControlStyle CssClass="text" Width="100px" />
             <HeaderStyle CssClass="textBold" />
             <ItemStyle CssClass="text" HorizontalAlign="Center" Width="100px" />
         </asp:TemplateField>
         <asp:CommandField ShowInsertButton="True"
         ShowEditButton="True" ShowDeleteButton="True"
         ButtonType="Button" ShowSelectButton="False"  />
     </Columns>
     <EditRowStyle HorizontalAlign="Left" />
     <HeaderStyle BackColor="#E7EFF7" HorizontalAlign="Left" />
     <RowStyle HorizontalAlign="Left" />
     <SelectedRowStyle HorizontalAlign="Left" />
 </asp:GridView>

Open in new window

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Here's to Code Behind:

Imports Microsoft.VisualBasic
Imports System.Data
Imports System.Data.OleDb
Imports States_All
Imports VMOS

Partial Class VMOS_OrderHistory
    Inherits System.Web.UI.Page

    Public thisID As String
    Public ds As DataSet
    Public row As DataRow
    Public orderID As Integer

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        Dim thisPage As String = Request.Url.ToString  'Check Security
        If (checkSession(thisPage) = "False") Then
            Response.Redirect("../indexTools.aspx")
        End If

        '~~~~~~~~~~~~~~~    ORDER INFORMATION   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

        thisID = Request.QueryString("j")    'Contains Order#
        If (Not IsPostBack) Then
            bind()
        End If

    End Sub


Protected Sub gvOrderDetails_RowUpdating(sender As Object, e As System.Web.UI.WebControls.GridViewUpdateEventArgs) Handles gvOrderDetails.RowUpdating
        Dim con As New OleDbConnection
        Dim row As GridViewRow = DirectCast(gvOrderDetails.Rows(e.RowIndex), GridViewRow)

        Dim idLbl As New Label
        idLbl = DirectCast(row.Cells(0).FindControl("lblID"), Label)
        lbl8.text = idLbl.text         '~~~~~~~~~~~~~  This Works 

        Dim qtyTxt As New TextBox
        [b]qtyTxt = DirectCast(row.Cells(1).FindControl("txtQty"), TextBox)   '~~~~~~~~~~  Blows up Here[/b]

        'Dim prodTxt As New TextBox
        'prodTxt = DirectCast(row.Cells(2).FindControl("txtProd"), TextBox)
        'Dim yearTxt As New TextBox
        'yearTxt = DirectCast(row.Cells(3).FindControl("txtYear"), TextBox)
        'Dim priceTxt As New TextBox
        'priceTxt = DirectCast(row.Cells(4).FindControl("txtPrice"), TextBox)
        'Dim costTxt As New TextBox
        'costTxt = DirectCast(row.Cells(5).FindControl("txtCost"), TextBox)
        'Dim shipTxt As New TextBox
        'shipTxt = DirectCast(row.Cells(6).FindControl("txtShip"), TextBox)

        Dim strSQL As String

        strSQL = "Update Order_Details SET "
        strSQL = strSQL + "Product_ID = ?, Quantity = ?, Price = ?, Product_Year = ?, Item_Total = ?, Item_Shipped = ? "
        strSQL = strSQL + "WHERE (Order_Details_ID = ?)"

        con = addData()
        Dim cmd As New OleDbCommand
        cmd = New OleDbCommand(strSQL, con)

        'Using con
        '    Using cmd As New OleDbCommand(strSQL, con)
        '        cmd.CommandType = CommandType.Text
        '        cmd.Parameters.AddWithValue("Product_ID", prodTxt.Text)
        '        cmd.Parameters.AddWithValue("Quantity", qtyTxt.Text)
        '        cmd.Parameters.AddWithValue("Price", priceTxt.Text)
        '        cmd.Parameters.AddWithValue("Product_Year", yearTxt.Text)
        '        cmd.Parameters.AddWithValue("Item_Total", costTxt.Text)
        '        cmd.Parameters.AddWithValue("Item_Shipped", shipTxt.Text)
        '        cmd.Parameters.AddWithValue("Order_Details_ID", idLbl.Text)
        '        con.Open()
        '        cmd.ExecuteNonQuery()
        '    End Using
        'End Using

        gvOrderDetails.EditIndex = -1

        bind()

    End Sub

  Sub bind()
        Dim strSQL As String

        strSQL = "SELECT * FROM Order_Details "
        strSQL = strSQL + "WHERE Order_ID = " & thisID & " "
        strSQL = strSQL + "ORDER BY Order_Details_ID"
        ds = GetData(strSQL)
        gvOrderDetails.DataSource = ds
        gvOrderDetails.DataBind()

    End Sub

Open in new window

Any ideas?

JS

Christopher Kile

Try using the Label in the item template as your base type, and cast to a Label object just to see what happens. I say this because, as you point out, your first field cast works - you may no longer be in edit mode when the row is updating.

Obadiah Christopher

lblID is part of the ItemTemplate.

txtQty is part of the EditItemTemplate.

Christopher Kile

BTW, that suggestion hasn't been tested by me, and is in the nature of a guess.

JS List

ASKER

I tried the label choice and no luck. The lbl that works is actually a label in the form that's hidden - it's the order-detail id #.

Item Template vs EditItemTemplate -
After the user enters a change value, in the edit text box - then it goes to the RowUpdating sub. At that point should I call the EditItemTemplate or the ItemTemplate to get the change?

Christopher Kile

I would try the objects in the EditItemTemplate. This is where the items edited should be.

ASKER CERTIFIED SOLUTION

JS List

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Christopher Kile

LOL next time I'll ask, "Did you create it in a wizard? Can you recreate it?" Good catch.

JS List

ASKER

While the information was helpful there was no clear answer submitted. I recreated it with the wizard.