How to validate a edit item template in gridview whn updatin

Question

Hi, how do I validate an edit item template in gridview when updating the data without using asp.net validation controls.

Please look at the code:

 

<asp:GridView ID="gvPhoneBook" runat="server" AutoGenerateColumns="false"

ShowFooter="true" DataKeyNames="PhoneBookID"

ShowHeaderWhenEmpty="true"

OnRowCommand="gvPhoneBook_RowCommand"

OnRowEditing="gvPhoneBook_RowEditing" OnRowCancelingEdit="gvPhoneBook_RowCancelingEdit"

OnRowUpdating="gvPhoneBook_RowUpdating" OnRowDeleting="gvPhoneBook_RowDeleting"

BackColor="White" BorderColor="#CCCCCC" BorderStyle="None"

BorderWidth="1px" CellPadding="3">

<%-- Theme Properties --%>

<FooterStyle BackColor="White" ForeColor="#000066" />

<HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" />

<PagerStyle BackColor="White" ForeColor="#000066" Horizontal />

<RowStyle ForeColor="#000066" />

<SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />

<SortedAscendingCellStyle BackColor="#F1F1F1" />

<SortedAscendingHeaderStyle BackColor="#007DBB" />

<SortedDescendingCellStyle BackColor="#CAC9C9" />

<SortedDescendingHeaderStyle BackColor="#00547E" />

<Columns>

<asp:TemplateField HeaderText="First Name">

<ItemTemplate>

<asp:Label Text='<%# Eval("FirstName") %>' runat="server" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtFirstName" Text='<%# Eval("FirstName") %>' runat="server" />

</EditItemTemplate>

<FooterTemplate>

<asp:TextBox ID="txtFirstNameFooter" runat="server" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="Last Name">

<ItemTemplate>

<asp:Label Text='<%# Eval("LastName") %>' runat="server" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtLastName" Text='<%# Eval("LastName") %>' runat="server" />

</EditItemTemplate>

<FooterTemplate>

<asp:TextBox ID="txtLastNameFooter" runat="server" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="Contact">

<ItemTemplate>

<asp:Label Text='<%# Eval("Contact") %>' runat="server" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtContact" Text='<%# Eval("Contact") %>' runat="server" />

</EditItemTemplate>

<FooterTemplate>

<asp:TextBox ID="txtContactFooter" runat="server" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="Email">

<ItemTemplate>

<asp:Label Text='<%# Eval("Email") %>' runat="server" />

</ItemTemplate>

<EditItemTemplate>

<asp:TextBox ID="txtEmail" Text='<%# Eval("Email") %>' runat="server" />

</EditItemTemplate>

<FooterTemplate>

<asp:TextBox ID="txtEmailFooter" runat="server" />

</FooterTemplate>

</asp:TemplateField>

<asp:TemplateField>

<ItemTemplate>

<asp:ImageButton ImageUrl="~/Images/edit.png" runat="server" CommandName="Edit" ToolTip="Edit" Width="20px" Height="20px"/>

<asp:ImageButton ImageUrl="~/Images/delete.png" runat="server" CommandName="Delete" ToolTip="Delete" Width="20px" Height="20px"/>

</ItemTemplate>

<EditItemTemplate>

<asp:ImageButton ImageUrl="~/Images/save.png" runat="server" OnClientClick="ValidateGridview()" CommandName="Update" ToolTip="Update" Width="20px" Height="20px"/>

<asp:ImageButton ImageUrl="~/Images/cancel.png" runat="server" CommandName="Cancel" ToolTip="Cancel" Width="20px" Height="20px"/>

</EditItemTemplate>

<FooterTemplate>

<asp:ImageButton ImageUrl="~/Images/addnew.png" runat="server" CommandName="AddNew" ToolTip="Add New" Width="20px" Height="20px"/>

</FooterTemplate>

</asp:TemplateField>

</Columns>

</asp:GridView>

 

 

 I want to validate first name and contact only?? How do i do that?? Please help