从Gridview DropDownList读取数据

Question

这个确切的代码适用于另一个页面，但不适用于我正在处理的页面。我从我的其他页面复制并粘贴它，但无法弄清楚什么是错误的。希望它很容易。

我有一个gridview，它有一些下拉列表和文本框。当我单击btnApproveSave按钮时，它应该读取gridview中的数据，然后对数据库执行更新。但是，c＃不会为gridview的每一行中的下拉列表或文本框读取任何内容。

<asp:Button ID="btnApprove" runat="server" OnClick="btnApprove_Click" Text="Submit Approval" />
            &nbsp;&nbsp;&nbsp;
            <asp:Button ID="btnApproveSave" runat="server" Text="Save Entries" OnClick="btnApproveSave_Click" />
            <br />
            <asp:Label ID="lblError" runat="server" Text="Please Verify That All Fields Have Been Filled Out" Visible="false" ForeColor="#D71826" />
            <br />
            <br />
            <div class="form-group">
                <asp:GridView ID="gvCreditCards" runat="server" Visible="true" ShowHeaderWhenEmpty="true" AutoGenerateColumns="false">
                    <Columns>
                        <asp:BoundField DataField="id" HeaderText="ID" ItemStyle-CssClass="gvCCPadding" />
                        <asp:BoundField DataField="fin_transaction_date" HeaderText="Transaction Date" ItemStyle-CssClass="gvCCPadding" ItemStyle-Width="50%" DataFormatString="{0:MM/dd/yyyy}" />
                        <asp:BoundField DataField="acc_account_name" HeaderText="Account Name" ItemStyle-CssClass="gvCCPadding minWidth" />
                        <asp:BoundField DataField="fin_charge" HeaderText="Charge" ItemStyle-CssClass="gvCCPadding" DataFormatString="{0:C}" ItemStyle-HorizontalAlign="Right" />
                        <asp:BoundField DataField="fin_transaction_description" HeaderText="Vendor Name" ItemStyle-CssClass="gvCCPadding minWidth" />
                        <asp:BoundField DataField="mch_state_province" HeaderText="State" ItemStyle-CssClass="gvCCPadding" />
                        <asp:TemplateField HeaderText="Description" ControlStyle-Width="150px">
                            <ItemTemplate>
                                <asp:TextBox ID="txtUserDescription" runat="server" Text='<%# Eval("toa_user_description") %>' />
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Receipt (Y/N)" ControlStyle-Width="75px">
                            <ItemTemplate>
                                <asp:DropDownList ID="ddlReceipt" runat="server">
                                    <asp:ListItem Text="" Selected="True" Value=""></asp:ListItem>
                                    <asp:ListItem Text="Yes" Selected="False" Value="Yes"></asp:ListItem>
                                    <asp:ListItem Text="No" Selected="False" Value="No"></asp:ListItem>
                                </asp:DropDownList>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="GL Code" ControlStyle-Width="200px">
                            <ItemTemplate>
                                <asp:DropDownList ID="ddlGLCode" runat="server" DataSourceID="ds_AccountCode" DataValueField="toa_account_name" AppendDataBoundItems="true">
                                    <asp:ListItem Selected="True" Text="" Value=""></asp:ListItem>
                                </asp:DropDownList>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Department" ControlStyle-Width="200px">
                            <ItemTemplate>
                                <asp:DropDownList ID="ddlDepartment" runat="server" DataSourceID="ds_Department" DataValueField="toa_businessDepartment" AppendDataBoundItems="true">
                                    <asp:ListItem Selected="True" Text="" Value=""></asp:ListItem>
                                </asp:DropDownList>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Location" ControlStyle-Width="200px">
                            <ItemTemplate>
                                <asp:DropDownList ID="ddlLocation" runat="server" DataSourceID="ds_businessLocation" DataValueField="toa_site" AppendDataBoundItems="true">
                                    <asp:ListItem Selected="True" Text="" Value=""></asp:ListItem>
                                </asp:DropDownList>
                            </ItemTemplate>
                        </asp:TemplateField>
                    </Columns>
                    <AlternatingRowStyle BackColor="#e9e9e9" />
                    <HeaderStyle BackColor="#e9e9e9" ForeColor="#D71826" />
                    <EmptyDataTemplate>
                        Empty Gridview
                    </EmptyDataTemplate>
                    <EmptyDataRowStyle ForeColor="#D71826" />
                </asp:GridView>
            </div>
        </div>
    </div>


    <asp:SqlDataSource ID="ds_AccountCode" runat="server" ConnectionString="<%$ ConnectionStrings:TOA_LIVEConnectionString %>"
        SelectCommand="SELECT [toa_account_name] FROM [toa_AccountCode]"></asp:SqlDataSource>


    <asp:SqlDataSource ID="ds_Department" runat="server" ConnectionString="<%$ ConnectionStrings:TOA_LIVEConnectionString %>"
        SelectCommand="SELECT [toa_businessDepartment] FROM [toa_Department]"></asp:SqlDataSource>


    <asp:SqlDataSource ID="ds_businessLocation" runat="server" ConnectionString="<%$ ConnectionStrings:TOA_LIVEConnectionString %>"
        SelectCommand="SELECT [toa_site] FROM [toa_Location]"></asp:SqlDataSource>
</asp:Content>

C＃

protected void btnApprove_Click(object sender, EventArgs e)
    {
        foreach (GridViewRow row in gvCreditCards.Rows)
        {
            string id = row.Cells[0].Text;
            TextBox tDESCRIPTION = (TextBox)row.FindControl("txtUserDescription");
            string sDESCRIPTION = tDESCRIPTION.Text;
            DropDownList ddlRECEIPT = (DropDownList)row.FindControl("ddlReceipt");
            string sRECEIPT = ddlRECEIPT.SelectedValue;
            DropDownList ddlGLCODE = (DropDownList)row.FindControl("ddlGLCode");
            string sDDLCODE = ddlGLCODE.SelectedValue;
            DropDownList ddlDEPARTMENT = (DropDownList)row.FindControl("ddlDepartment");
            string sDEPARTMENT = ddlDEPARTMENT.SelectedValue;
            DropDownList ddlLOCATION = (DropDownList)row.FindControl("ddlLocation");
            string sLOCATION = ddlLOCATION.SelectedValue;

            foreach (var v in new object[] { sDESCRIPTION, sRECEIPT, sDDLCODE, sDEPARTMENT, sLOCATION })
            {
                if (v.ToString() == "")
                {
                    btnApproveSave_Click(sender, e);
                    Response.Redirect(string.Format("http://transovaapps/TransOvaApps/departments/Accounting/CreditCard/CreditCardApprovals.aspx?emptyValue=true"));
                }
            }
        }