Row Edit event handler issue - asp.net

Question

<asp:GridView ID="GridView1" runat="server"
style="height: 121px; width: 175px" BackColor="White"
BorderColor="#3366CC" BorderStyle="None" BorderWidth="1px" CellPadding="4"
onrowediting="GridView1_RowEditing" AutoGenerateColumns="false">
<Columns>
<asp:CommandField ButtonType="Button" SelectText="Edit" ShowEditButton="true" />
<asp:TemplateField>
<ItemTemplate>
<asp:Label ID="lblId" runat="server" Text='<%# Eval("Id") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="TextBox1" runat="server" Text='<%# Eval("Id") %>'></asp:TextBox>
</EditItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:Label ID="lblCpuName" runat="server" Text='<%# Eval("cpuname") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="TextBox2" runat="server" Text='<%# Eval("cpuname") %>'></asp:TextBox>
</EditItemTemplate>
</asp:TemplateField>
<asp:TemplateField>
<ItemTemplate>
<asp:Label ID="lblStatus" runat="server" Text='<%# Eval("status") %>'></asp:Label>
</ItemTemplate>
<EditItemTemplate>
<asp:TextBox ID="TextBox3" runat="server" Text='<%# Eval("status") %>'>></asp:TextBox>
</EditItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
SqlDataSource1.UpdateCommandType = SqlDataSourceCommandType.Text;
GridViewRow row = GridView1.Rows[e.NewEditIndex];
TextBox txt = (TextBox)row.FindControl("TextBox2");
SqlDataSource1.UpdateParameters["CpuName"].DefaultValue = txt.Text;
SqlDataSource1.UpdateParameters["cpuid"].DefaultValue = "3";
SqlDataSource1.Update();
BindGridView();
}
I am getting a object reference not set to an object on the textbox txt. I am not able to get the textbox2 in my gridview.

Answer 1

Can you try this
GridViewRow row = GridView1.Rows[GridView1.NewEditIndex];
TextBox txt = row.Cells[1].Controls[1] as TextBox;
If (txt!= null)
{
SqlDataSource1.UpdateParameters["CpuName"].DefaultValue = txt.Text;
SqlDataSource1.UpdateParameters["cpuid"].DefaultValue = "3";
SqlDataSource1.Update();
BindGridView();
}

Answer 2

Why you just don't get directly the textbox value? is this a great problem?
...
GridViewRow row = GridView1.Rows[e.NewEditIndex];
SqlDataSource1.UpdateParameters["CpuName"].DefaultValue = row.Columns["CpuName"].Value;
...
I don't know that this works, because I'm a C#-er, and basically work on winform not on web apps

Answer 3

First, here is the snippet from MSDN, RowEditing topic:
The RowEditing event is raised when a
row's Edit button is clicked, but
before the GridView control enters
edit mode. This enables you to provide
an event-handling method that performs
a custom routine, such as canceling
the edit operation, whenever this
event occurs.
To resolve the problem, handle the RowUpdating event for this purpose. There is an example which should be helpful to you at:
GridView.RowEditing event
Also, I believe you should use the Bind word to bind your TextBox to a field:
'>
For more details, please refer to the Data-Binding Expressions Overview