Controls within panel not accessible

Question

Hi i am trying to get all the textboxes on my form and trying to attach a eventhandler to all of them but i found out that since the textboxes are spread in multiple panels on my form, my existing code cannot access them . please suggest a solution

   private void StockitemCDA_Load(object sender, EventArgs e)
        {  
         // add all controls having type starting from customtextbox bind to same textbox 
           Controls
           .OfType<customtextbox>()
           .ToList()
           .ForEach(b => { b.TriggerEvent += OnTriggerEvent; });
            
        


        }
    

        private void OnTriggerEvent(bool last, string name)

        {
            if (last)
            {
                       //    do something here 



            }
        }

Answer 1

Here is an example using a standard TextBox. Descendants gets all controls on a form no matter where they are and TextBoxList in this case filters down to TextBox controls so model one for your custom control.

public static class ControlExtensions
{

    public static IEnumerable<T> Descendants<T>(this Control control) where T : class
    {
        foreach (Control child in control.Controls)
        {
            if (child is T thisControl)
            {
                yield return (T)thisControl;
            }

            if (child.HasChildren)
            {
                foreach (T descendant in Descendants<T>(child))
                {
                    yield return descendant;
                }
            }
        }
    }
    public static List<TextBox> TextBoxList(this Control control) 
        => control.Descendants<TextBox>().ToList();
}

In a form

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        this.TextBoxList().ForEach(tb => 
            tb.Click += delegate (object tb, EventArgs args) {
            Debug.WriteLine(((TextBox)tb).Name);
        });
    }
}

Answer 2

Hi @rahul kumar , Welcome to Microsoft Q&A.

All the textboxes in the program are considered in the code example, and you can add only the controls in the panel using a similar method.

What I added here is the click event as a demonstration, you can add the corresponding event you want.

For example:

foreach (Control childControl in control.Controls)
{
    if (childControl is Panel)
    {
        foreach (Control control1 in childControl.Controls)
        {
            if (control1 is CustomTextBox)
            {
                CustomTextBox textBox = (CustomTextBox)childControl;
                textBox.Click += OnTriggerEvent;
            }
        }
    }
}

Here's the full code:

using _6_xx_uc2;
using System;
using System.Windows.Forms;

namespace _6_xx_1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            AttachEventHandlers(this);
        }

        private void AttachEventHandlers(Control control)
        {
            foreach (Control childControl in control.Controls)
            {
                if (childControl is CustomTextBox)
                {
                    CustomTextBox textBox = (CustomTextBox)childControl;
                    textBox.Click += OnTriggerEvent;
                }
                else if (childControl.HasChildren)
                {
                    AttachEventHandlers(childControl);
                }
            }
        }

        private void OnTriggerEvent(object sender, EventArgs e)
        {
            CustomTextBox customTextBox = (CustomTextBox)sender;
            customTextBox.Text = customTextBox.Name;
        }

    }
}

Best Regards,

Jiale

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