how to get the detailsview textbox field value where DefaultMode is Edit

<asp:DetailsView ID="dvCategory" runat="server" AutoGenerateRows="False"
              DataKeyNames="iCategoryID" Width="90%" GridLines="None"
              OnItemInserting="dvCategory_ItemInserting"
              OnItemUpdating="dvCategory_ItemUpdating"
              OnModeChanging="dvCategory_ModeChanging" ondatabound="dvCategory_DataBound" >
             <Fields>
                 <asp:BoundField DataField="iCategoryID" HeaderText="ID" InsertVisible="False" ReadOnly="True" />
                 <asp:TemplateField HeaderText="Name">
                      <EditItemTemplate>
                        <asp:TextBox ID="txtCategoryName" runat="server" Text='<%# Bind("strCategoryName") %>'></asp:TextBox>
                        <asp:RequiredFieldValidator ID="rfvCategoryName" runat="server" ControlToValidate="txtCategoryName"
                        Display="Dynamic" ErrorMessage="Name" SetFocusOnError="True">*</asp:RequiredFieldValidator>
                      </EditItemTemplate>
                      <InsertItemTemplate>
                         <asp:TextBox ID="txtCategoryName" runat="server" Text='<%# Bind("strCategoryName") %>'></asp:TextBox>
                         <asp:RequiredFieldValidator ID="rfvCategoryName" runat="server" ControlToValidate="txtCategoryName"
                          Display="Dynamic" ErrorMessage="Name" SetFocusOnError="True">*</asp:RequiredFieldValidator>
                      </InsertItemTemplate>
                      <ItemTemplate>
                          <asp:Label ID="lblCategoryName" runat="server" Text='<%# Bind("strCategoryName") %>'></asp:Label>
                     </ItemTemplate>
                  </asp:TemplateField>

                 <asp:CommandField ShowEditButton="True" ShowInsertButton="True" />
                  </Fields>
              </asp:DetailsView>