Get the list of Child controls inside a groupbox

Question

I have a groupbox in my application which contains child controls.(As seen in the attchached pic). I want to enumerate through all the textboxes for performing some validation using a simple foreach loop.

This document outline would give a fair idea of the housing of the controls

foreach (Control control in grpBxTargetSensitivity.Controls)
            {
                if (control is FlowLayoutPanel && control.HasChildren)
                {
                    foreach (Control ctrl in control.Controls)
                    {
                        if (ctrl is Panel && ctrl.HasChildren)
                        {
                            foreach (Control tbox in ctrl.Controls)
                            {
                                if (tbox is TextBox)
                                {
                                    TextBox textbox = tbox as TextBox;
                                    validData &= !string.IsNullOrWhiteSpace(textbox.Text);
                                }
                            }
                        }
                    }
                }
            }

My question is, Is there a better way (possibly through LINQ) to get all the controls including the textboxes housed inside the panels than the above method.?

Answer 1

I don't know that this is any better.. whether it's easier to read is a matter of opinion:

var validData
    = grpBxTargetSensitivity.Controls.OfType<FlowLayoutPanel>()
                            .SelectMany(c => c.Controls.OfType<Panel>())
                            .SelectMany(c => c.Controls.OfType<TextBox>())
                            .All(textbox => !string.IsNullOrWhiteSpace(textbox.Text));

This'll grab all TextBoxes inside of all Panels in all FlowLayoutPanels in your GroupBox, and return true if all of those TextBoxes have a value in them.

Answer 2

A one liner slution,

IEnumerable<TextBox> collection = grpBxTargetSensitivity.Children.OfType<TextBox>(); //assuming you are looking for TextBox

or

You can try following generic method,

public static IEnumerable<T> FindVisualChildren<T>(DependencyObject depObj) where T : DependencyObject
{
    if (depObj != null)
    {
        for (int i = 0; i < VisualTreeHelper.GetChildrenCount(depObj); i++)
        {
            DependencyObject child = VisualTreeHelper.GetChild(depObj, i);
            if (child != null && child is T)
            {
                yield return (T)child;
            }

            foreach (T childOfChild in FindVisualChildren<T>(child))
            {
                yield return childOfChild;
            }
        }
    }
}

then enumerate over the controls as follows,

foreach (TextBox tb in FindVisualChildren<TextBox>(grpBxTargetSensitivity)) //assuming you are looking for TextBox
{
    // do something
}