itemTemplate item id not existing in code behind - asp.net

Question

I am trying to create textboxes that are equal to the number of rows in grid view (databound from db). here is my markup
<asp:GridView ID="quizGrid" runat="server" CssClass="Grid" AutoGenerateColumns="false">
<Columns>
<asp:BoundField DataField="admissionNO" HeaderText="Admission NO"/>
<asp:BoundField DataField="studentName" HeaderText="Name" />
<asp:TemplateField>
<ItemTemplate>
<asp:Textbox runat="server" ID="marks" > </asp:Textbox>
</ItemTemplate>
</asp:TemplateField>
</Columns>
but when i use the marks in code behind it says
quizGrid_marks_0 does not exists in the current context
what im doing wrong here?

Answer 1

You can't access your textbox like that in code behind file, rather you need to find them in RowDataBound event like this:-
protected void quizGrid_RowDataBound(object sender, GridViewRowEventArgs e)
{
if(e.Row.RowType == DataControlRowType.DataRow)
{
TextBox marks = (TextBox)e.Row.FindControl("marks");
txtMarks.Text = "Test";
}
}
Edit:
Okay, suppose you have a button btnGetData with button click event as btnGetData_Click, then you can find the textbox text by looping through the gridview rows like this:-
protected void btnGetData_Click(object sender, EventArgs e)
{
GridView quizGrid = (GridView)Page.FindControl("quizGrid");
foreach (GridViewRow row in quizGrid.Rows)
{
TextBox marks = (TextBox)row.FindControl("marks");
}
}