find control in page
HTML
<body>
<form id="form1" runat="server">
<asp:Button runat="server" ID="a" OnClick="a_Click" Text="apd"/>
</form>
</body>
Code
protected void a_Click(object sender,EventArgs e)
{
Response.Write(((Button)FindControl("a")).Text);
}
This code works fine.
However, this code:
HTML
<%@ Page Title="" Language="C#" MasterPageFile="~/Student/MasterPage.master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="Student_Default" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<asp:Button runat="server" ID="a" OnClick="a_Click" Text="andj"/>
</asp:Content>
Code
protected void a_Click(object sender, EventArgs e)
{
Response.Write(((Button)FindControl("a")).Text);
}
This code does not work and FindControl returns Null - why is this?
The FindControl method works in a simple page fine, but in a master page, does it not work?
The ID of the a is changed to ctl00_ContentPlaceHolder1_a - how can find control?
Answer
To find the button on your content page you have to search for the ContentPlaceHolder1 control first.
Then use the FindControl function on the ContentPlaceHolder1 control to search for your button:
ContentPlaceHolder cph = (ContentPlaceHolder)this.Master.FindControl("ContentPlaceHolder1");
Response.Write(((Button)cph.FindControl("a")).Text);