WPF how do I create a textbox dynamically and find the textbox on a button click?

David Basarab picture David Basarab · Feb 11, 2009 · Viewed 50.5k times · Source

I am creating a TextBox and a Button dynamically using the following code:

Button btnClickMe = new Button();
btnClickMe.Content = "Click Me";
btnClickMe.Name = "btnClickMe";
btnClickMe.Click += new RoutedEventHandler(this.CallMeClick);

someStackPanel.Childern.Add(btnClickMe);

TextBox txtNumber = new TextBox();
txtNumber.Name = "txtNumber";
txtNumber.Text = "1776";

someStackPanel.Childern.Add(txtNumber);

I hook up to a click event to the Click Me button. The click me button even is fired correctly. However I cannot find the TextBox I entered dynamically.

Here is my click me event:

protected void ClickMeClick(object sender, RoutedEventArgs e)
{
    // Find the phone number
    TextBox txtNumber = this.someStackPanel.FindName("txtNumber") as TextBox;

    if (txtNumber != null)
    {
        string message = string.Format("The number is {0}", txtNumber.Text);

        MessageBox.Show(message);    
    }
    else
    {
        MessageBox.Show("Textbox is null");
    }
}

How can I find the TextBox txtNumber?

Answer

hughdbrown picture hughdbrown · Feb 11, 2009

Josh G had the clue that fixed this code: use RegisterName().

Three benefits here:

  1. Doesn't use a member variable to save the reference to the dynamically created TextBox.
  2. Compiles.
  3. Complete code.

    using System;
    using System.Windows;
    using System.Windows.Controls;
    
    namespace AddControlsDynamically
    {
        public partial class Window1 : Window
        {
            public void Window_Loaded(object sender, RoutedEventArgs e)
            {
                GenerateControls();
            }
            public void GenerateControls()
            {
                Button btnClickMe = new Button();
                btnClickMe.Content = "Click Me";
                btnClickMe.Name = "btnClickMe";
                btnClickMe.Click += new RoutedEventHandler(this.CallMeClick);
                someStackPanel.Children.Add(btnClickMe);
                TextBox txtNumber = new TextBox();
                txtNumber.Name = "txtNumber";
                txtNumber.Text = "1776";
                someStackPanel.Children.Add(txtNumber);
                someStackPanel.RegisterName(txtNumber.Name, txtNumber);
            }
            protected void CallMeClick(object sender, RoutedEventArgs e)
            {
                TextBox txtNumber = (TextBox) this.someStackPanel.FindName("txtNumber");
                string message = string.Format("The number is {0}", txtNumber.Text);
                MessageBox.Show(message);
            }
        }
    }