Problem FindControl in ContentPlaceHolder

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My ContentPlaceHolder:

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Dang.aspx.cs" Inherits="Dang" %>

<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">

<asp:Content ID="Content2" runat="server" contentplaceholderid="Content1">
    <asp:TextBox ID="txt" runat="server">

You can see Content1 and Content2.How to Fincontrol in ContentPlaceHolder?
I tried:

C#

TextBox t =(TextBox) Master.FindControl("Content1").FindControl("txt");
TextBox txtuser = (TextBox)Page.Master.FindControl("txtUser");
t.Text = txtuser.Text;

Masterpage:

C#

public partial class MasterPage : System.Web.UI.MasterPage
{
    protected void Page_Load(object sender, EventArgs e)
    {
        txtUser.Text = "John";
    }
}

But error occurs.

Posted 16-May-12 21:47pm

giatuan2011

Updated 16-May-12 21:49pm

sravani.v

v2

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Dain Ucak · Answer 1 · 2012-05-16T21:58:00

Solution 1

if you want to try find any control of content page in master page do this

C#

//Content1 is your ContentPlaceHolder id in master page
TextBox t =(TextBox)Content1.FindControl("txt");

Posted 16-May-12 21:58pm

Dain Ucak

v2

Comments

giatuan2011 17-May-12 4:01am

I tried your code and:
ContentPlaceHolder con = (ContentPlaceHolder)Page.Master.FindControl("Content1");
TextBox t = (TextBox)con.FindControl("txt");
TextBox txtuser = (TextBox)Page.Master.FindControl("txtUser");
t.Text is empty

Dain Ucak 17-May-12 5:15am

do you try this in your master page and whats your ContentPlaceHolder Id?

giatuan2011 17-May-12 6:22am

My ContentPlaceHolder Id is Content1 in Master.Asp.net 2005 and asp.net 2008 are different?What is Content2?
make Dang.aspx-> select master-> in design, I can not add anything to the ContentPlaceHolder.
I click CustomContent .. and Content 2 appears.
This is a problem?

Dain Ucak 17-May-12 6:40am

when you create a master page it create two contentplaceholders. one of them for head tags and other one for bodys. if you want to get any controls of content page like dang.aspx in your master page. TextBox txt = (TextBox)Content1.FindControl("txt"). this is enough for get any controls from content pages. if you didnt solve pls post your master page and content pages code. i will analyze it for you

giatuan2011 17-May-12 8:02am

TextBox t = (TextBox)con.FindControl("txt");
TextBox txtuser = (TextBox)Page.Master.FindControl("txtUser");
I tried:
t.Text = "Hello";
t.Text = txtuser.Text.ToString();
It appears "Hello" in textbox of the page Dang.aspx.
txtUser not change.
I not found Content1.It only has ContentPlaceHolder,Content,Page and Master.
How can I attach files?

Dain Ucak 17-May-12 8:09am

if you are in master page codebehind and txtUser is a content page control make this
TextBox txtuser = (TextBox)con.FindControl("txtUser"); correct here
else return me

giatuan2011 17-May-12 8:33am

you mean:in Dang.aspx,TextBox txtuser = (TextBox)con.FindControl("txtUser"); correct here?
txtUser is the control in Master.
txt is the control in ContentPlaceHolder.
When I remove txt,I can:
TextBox txtuser = (TextBox)Page.Master.FindControl("txtUser");
txtuser.Text="Hi,Guest";
After I add txt and change Master load:
protected void Page_Load(object sender, EventArgs e)
{
txtUser.Text = "Hi";
}
Dang.aspx:
TextBox txtuser = (TextBox)Page.Master.FindControl("txtUser");
txtuser.Text="change";
ContentPlaceHolder con=(ContentPlaceHolder)Page.Master.FindControl("Content1");
TextBox txt = (TextBox)con.FindControl("txt");
txt.Text = txtuser.Text;
txt is empty.txtUser is Hi.I can't change content of txtUser.

giatuan2011 17-May-12 8:52am

Oh,I clear txUser.Text in Master load and go to properties,change text of txtUser to Hi.
TextBox txtuser = (TextBox)con.FindControl("txtUser");
It works.I think problem is Master load:txtUser.Text="Hi".
So, How do I get and set txtUser after logging in without problem?

Dain Ucak 17-May-12 8:56am

contents pages loading event occuring before master pages loading event.
you can set controls property in master page load event and you can called in content pages unload event this property value. try this
you can call master pages control in content pages unload event

protected void Page_Unload(object sender, EventArgs e)
{
TextBox txtMaster = (TextBox)this.Master.FindControl("txtMaster");
}

giatuan2011 17-May-12 9:05am

yes.I can set txtUser in Master load.But
ContentPlaceHolder con=(ContentPlaceHolder)Page.Master.FindControl("Content1");
TextBox txt = (TextBox)con.FindControl("txt"); txt.Text = txtuser.Text;
It does not display content of txtUser.
"contents pages loading event occuring before master pages loading event."
Oh,I understand why the txt does not show.I add button called btnGet in Dang.aspx and txt displayed content of txtUser.I can set content of txtUser after click btnGet.
Thank you.

Dain Ucak 17-May-12 9:19am

now i do this step by step. and it work fine.
i have a textbox in content page and its id txtContent.
i have a textbox in master page and its id txtMaster.
this is master pages html sides
<form id="form1" runat="server">
<asp:TextBox ID="txtMaster" runat="server">
<asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">

and this is my content page html side codes
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<asp:TextBox ID="txtContent" runat="server">

and this is master page load event codes

TextBox txtContent = (TextBox)ContentPlaceHolder1.FindControl("txtContent");
txtContent.Text = txtMaster.Text;
forget unload event. tell me from this scenario.

giatuan2011 17-May-12 9:32am

I thought after load Dang.aspx,txtMaster will take the contents of txtContent.
But when I press the button btnGet, the content of txtMaster does not change.

Dain Ucak 17-May-12 9:40am

ok now. you mean you want to change any controls property of master page in content page button click? isnt it

giatuan2011 17-May-12 9:48am

I mean username and password in Login.aspx, click login.And txtUser appear: Hi, <username>
I tried:
string sname;
protected void Button1_Click(object sender, EventArgs e)
{
TextBox txtuser = (TextBox)Page.Master.FindControl("txtUser");
ContentPlaceHolder con = (ContentPlaceHolder)Master.FindControl("ContentPlaceHolder1");
TextBox tx = (TextBox)con.FindControl("txtusername");
txtuser = (TextBox)Page.Master.FindControl("txtUser");
sname = tx.Text;
txtuser.Text = sname;
}
It works.it is correct?

Dain Ucak 17-May-12 9:51am

cant you call txtusername directly in button1_click. why do you need do this
ContentPlaceHolder con = (ContentPlaceHolder)Master.FindControl("ContentPlaceHolder1");
TextBox tx = (TextBox)con.FindControl("txtusername");

giatuan2011 18-May-12 0:16am

I think I should use the Session.After logging in, the Session will save the username.I just need get the Session by refresh page.
I should put it to Pagel_load content page and mater
TextBox txtuser = (TextBox)Page.Master.FindControl("txtUser");
if (Session["username"] != null)
{
txtuser.Text = Session["userna"].ToString();
}else{
Session["username"] = "<get from="" database="">";
txtuser.Text = Session["username"].ToString();
}