asp.net get the text from a dynamically inserted textbox return null all the time - asp.net

Question

I am writing a web app in asp.net, in one of my aspx pages I have a static table.
To this table I insert a dynamically textbox control from the code behind (from Page_Load, I create this control dynamically because I do not know if I need to create it or not it depend on a user answer), the problem is when i try to get the textbox text after the user click on a button, I tried every thing i know from Request.Form.Get("id of the control") to Page.FindControl("id of the control"), but nothing works I get null all the time, just to be clear the button that activate the function that get the text from the textbox is insert dynamically to.
Both button and textbox are "sitting" in a table and must remain so, I'd appreciate any help
my code is:
aspx page
<asp:Table ID="TabelMessages" runat="server"></asp:Table>
code behind aspx.cs code:
protected void Page_Load(object sender, EventArgs e)
{
TextBox tb = new TextBox();
tb.ID = "textBox";
tb.Text = "hello world";
TableCell tc = new TableCell();
tc.Controls.Add(tb);
TableRow tr = new TableRow();
tr.Cells.Add(tc);
TabelMessages.Rows.Add(tr);
}
public void Button_Click(object o, EventArgs e)
{
string a = Request.Form.Get("textBox");//does not work
Control aa = Page.FindControl("textBox");//does not work
}

Answer 1

in your
public void Button_Click(object o, EventArgs e)
{
//try searching in the TableMessage.Controls()
}

Answer 2

Alternatively, and depending on what you ultimately want to do, and still use Page_Load:
In your Page Class:
protected TextBox _tb; //this is what makes it work...
protected void Page_Load(object sender, EventArgs e)
{
_tb = new TextBox();
_tb.ID = "textBox";
TableCell tc = new TableCell();
tc.Controls.Add(_tb);
TableRow tr = new TableRow();
tr.Cells.Add(tc);
TabelMessages.Rows.Add(tr);
if (!Page.IsPostBack)
{
_tb.Text = "hello world";
}
}
protected void Button1_Click(object sender, EventArgs e)
{
Label1.Text = _tb.Text; //this will display the text in the TextBox
}

Answer 3

You need to run your code inside the Page_PreInit method. This is where you need to add / re-add any dynamically created controls in order for them to function properly.
See more information about these types of issues in the MSDN article on the ASP.NET Page Life Cycle.

Answer 4

Try changing your Page_Load code to the following:
protected override void OnPreInit(EventArgs e)
{
base.OnPreInit(e);
TextBox tb = new TextBox();
tb.ID = "textBox";
tb.Text = "hello world";
TableCell tc = new TableCell();
tc.Controls.Add(tb);
TableRow tr = new TableRow();
tr.Cells.Add(tc);
TabelMessages.Rows.Add(tr);
}