保留asp.net中的动态控件

Question

I have page on which I have 10 panel controls. Each of these Panels have approx 10 TextBoxes which I create dynamically using following code

TextBox txt = new TextBox();
txt.ID = "txt_" + Month + "_" + Stage;
txt.Text = Value;
if (v == 0)
   Panel_0.Controls.Add(txt);
else if (v == 1)
   Panel_1.Controls.Add(txt);

I have some values retrieved from Database in those TextBoxes . I can change those values and I also have one Save button. On Click event of this button, I loop through TextBoxes of each panel to save modified data.

protected void btnSave_Click(object sender, EventArgs e)
{
    foreach (TextBox txt in Panel_0.Controls.OfType<TextBox>())
    {

    }
}

But, when I click on Save button, I can not find any TextBox Control in my for loop. Also on post back, these controls gets vanished from my page. How can I save the Controls and their Data so that I can retrieve it on Button Click event.

Answer 1

Dynamic controls are lost after postback. You have to re-created them after each post-back. you will have to make use of View-State

protected int NumberOfControls
{
    get{return (int)ViewState["NumControls"];}
    set{ViewState["NumControls"] = value;}
}


private void addSomeControl()
{
    TextBox tx = new TextBox();
    tx.ID = "ControlID_" + NumberOfControls.ToString();
    Page.Controls.Add(tx);
    this.NumberOfControls++;
}

Please visit the following Urls:

ASP.Net Dynamic Controls ViewState: Retain state for dynamically created controls on PostBack

Retaining State for Dynamically Created Controls in ASP.NET applications

ViewState in Dynamic Control