如何在asp.net中的网格视图文本框中编辑之前获取先前的值

Question

我正在使用对象数据源在网格视图上应用编辑功能。我想在我点击编辑按钮时需要以前的值，这里需要另一个目的我正在尝试编写代码但是它给出了当前的值。以前的价值.......希望你能帮帮我

 protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        GridViewRow row = (GridView1.Rows[e.RowIndex] as GridViewRow);

        string totalQuantity = (row.Cells[5].Controls[0] as TextBox).Text;//It gives current value but i want previous value
        string totalPurchasePrice = (row.Cells[6].Controls[0] as TextBox).Text; //It gives current value but i want previous value
        GridView1.EditIndex = -1;

        //value store in session start
        Session["totalQuantity"] = totalQuantity;
        Session["totalPurchasePrice"] = totalPurchasePrice;                       
        //value store in session end

    }

  

和网格视图代码

 <asp:GridView ID="GridView1" runat="server" CssClass="dataGridTable" AutoGenerateColumns="False" Width="100%" AllowPaging="True" BackColor="White" BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px" CellPadding="3" DataSourceID="ObjectDataSource1" HeaderStyle-Height="30" OnRowCreated="GridView1_RowCreated" PageSize="30" DataKeyNames="invoiceNumber,productName,productCategory" OnSelectedIndexChanged="GridView1_SelectedIndexChanged" OnRowUpdating="GridView1_RowUpdating">
                        <Columns>

                            <asp:CommandField ShowEditButton="true" ShowSelectButton="True" />
                            <asp:CommandField ShowDeleteButton="true"/>
                            <asp:BoundField DataField="invoiceNumber" HeaderText="Invoice" ReadOnly="true" SortExpression="invoiceNumber" />
                            <asp:BoundField DataField="productName" HeaderText="Name" ReadOnly="true" SortExpression="productName" />
                            <asp:BoundField DataField="productCategory" HeaderText="Category" ReadOnly="true" SortExpression="productCategory" />
                            <asp:BoundField DataField="totalQuantity" HeaderText="Quantity" SortExpression="totalQuantity" />
                            <asp:BoundField DataField="totalPurchasePrice" HeaderText="Total Price" SortExpression="totalPurchasePrice" />
                            <asp:BoundField DataField="salePricePerItem" HeaderText="Sale Price/Item" SortExpression="salePricePerItem" />
                            <asp:BoundField DataField="comments" HeaderText="Comments" SortExpression="comments" />
                            <asp:BoundField DataField="date" HeaderText="Date" ReadOnly="true" SortExpression="date" />


                             <asp:TemplateField>
                                <ItemTemplate>
                                    <asp:ImageButton ID="ImageButton1" runat="server" Height="24px" ImageUrl="~/Images/detailsInfo.png" Width="24px" OnClick="ImageButton1_Click" />
                                </ItemTemplate>
                            </asp:TemplateField>

                        </Columns>

                        <FooterStyle BackColor="White" ForeColor="#000066" />
                        <HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" CssClass="gridHeaderAlignment" />
                        <PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />
                        <RowStyle ForeColor="#000066" HorizontalAlign="Center" VerticalAlign="Middle" />
                        <HeaderStyle HorizontalAlign="Center" VerticalAlign="Middle" />
                        <SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
                        <SortedAscendingCellStyle BackColor="#F1F1F1" />
                        <SortedAscendingHeaderStyle BackColor="#007DBB" />
                        <SortedDescendingCellStyle BackColor="#CAC9C9" />
                        <SortedDescendingHeaderStyle BackColor="#00547E" />
                    </asp:GridView>