Build List utilizing for loop not populating list

Question

Hello - I'm trying to clear values associated with a checkbox list when a checkbox changes state to unchecked. The winform layout is: checkbox -> label -> combobox -> combobox-> textbox with 10 checkboxes. I can accomplish it thru brute force but am attempting to use a "for" loop to build a list of statements to clear appropriate form controls. I've attempted various approaches to no avail. This is where my code currently stands:

        private List<string> flushForm00()
        {
            var flushFields = new List<string>();
           //flushFields.Clear();

            if (placeLevel00CB.Checked == false)
            {   for (int i = 0; i < 10; i++) 
                {   string flushEachN = $"PlaceComboBox0{i}.Text = \"\";";
                    //string flushEachT = $"TypeComboBox0{i}.Text = \"\";";
                    Console.WriteLine(flushEachN);
                    Console.WriteLine($"TypeComboBox0{i}.Text = \"\";");
                    flushFields.Add(flushEachN);
                    flushFields.Add($"TypeComboBox0{i}.Text = \"\";");
                }
                for (int i = 1; i < 10; i++)
                {   string flushEachC = $"placeLevel0{i}.Checked = false;";
                    flushFields.Add(flushEachC);
                    Console.WriteLine(flushEachC);
                }
            }

            Console.WriteLine(flushFields);
            return flushFields;
        }

The loop is functioning properly as can be seen from console writes:
[OUTPUT]
PlaceComboBox00.Text = "";
TypeComboBox00.Text = "";
...
PlaceComboBox09.Text = "";
TypeComboBox09.Text = "";
placeLevel01.Checked = false;
placeLevel02.Checked = false;
...
placeLevel08.Checked = false;
placeLevel09.Checked = false;
System.Collections.Generic.List`1[System.String]

I've previously used the listName.Add("text") approach to populate a list so I'm at a loss to understand why this isn't working.

Thank you in advance for your time & expertise,
Art

Answer 1

Hello @Art Hansen

The following code sample uses a Tablelayoutpanel (secondary thought was a DataGridView formatted to look the same as the TableLayoutPanel but that takes more code). Each control has it's tag property set, first row the CheckBox and two ComboBox controls tag is 0, moving on to the last row the tag is 9. This should get you going.

Full source code

Extensions class

using System;  
using System.Text.RegularExpressions;  
  
namespace ClearControlsWindowsForms.Extensions  
{  
    public static class ControlHelpers  
    {  
        public static int GetInt(this string sender) => Convert.ToInt32(Regex.Match(sender, @"\d+\.*\d*").Value) - 1;  
    }  
}  

Form code

using ClearControlsWindowsForms.Extensions;  
using System;  
using System.Collections.Generic;  
using System.ComponentModel;  
using System.Data;  
using System.Diagnostics;  
using System.Drawing;  
using System.Linq;  
using System.Text;  
using System.Threading.Tasks;  
using System.Windows.Forms;  
  
namespace ClearControlsWindowsForms  
{  
    public partial class MainForm : Form  
    {  
        public MainForm()  
        {  
            InitializeComponent();  
  
            tableLayoutPanel1.Controls.OfType<CheckBox>().ToList()  
                .ForEach(cb => cb.CheckStateChanged += OnCheckStateChanged);  
        }  
  
        private void OnCheckStateChanged(object sender, EventArgs e)  
        {  
            if (_working)  
            {  
                return;  
            }  
              
            var cb = (CheckBox)sender;  
            if (cb.Checked) return;  
              
            var checkBoxIndex = cb.Name.GetInt() ;  
            var checkBoxes = tableLayoutPanel1.Controls.OfType<CheckBox>().ToList();  
  
            foreach (var checkBox in checkBoxes)  
            {  
                var cbIndex = checkBox.Name.GetInt();  
                if (cbIndex <= checkBoxIndex)  
                {  
                    checkBox.Checked = true;  
                      
                }  
                else  
                {  
                    checkBox.Enabled = false;  
                    var tagIndex = Convert.ToInt32(checkBox.Tag);  
                      
                    var controls = tableLayoutPanel1  
                        .Controls.OfType<ComboBox>()  
                        .Where(c => Convert.ToInt32(c.Tag) == tagIndex);  
                      
                    foreach (var comboBox in controls)  
                    {  
                        comboBox.Enabled = false;  
                    }  
                      
                }  
            }  
  
        }  
  
        private bool _working;  
        private void ResetButton_Click(object sender, EventArgs e)  
        {  
            _working = true;  
              
            foreach (var control in tableLayoutPanel1.Controls.OfType<ComboBox>())  
            {  
                control.Enabled = true;  
            }  
              
            foreach (var control in tableLayoutPanel1.Controls.OfType<CheckBox>())  
            {  
                control.Enabled = true;  
                control.Checked = false;  
            }  
  
            _working = false;  
        }  
    }  
  
  
}  

Note in the screenshot below the ComboBoxes are not populated an the reset button brings everything back as if the app just started.

Answer 2

I'm using an answer as a comment is limited. Note the downside to the following is it's not easy to use when you may want to replace existing controls, works best when starting new.

• Class project with controls
• Front end test project

Class project with controls

Good to hear this. One more thing a tad off topic is to consider using custom controls that has a property of type int in place of Tag.

For a CheckBox

public class CheckBoxCustom : CheckBox  
{  
    [Category("Behavior"), Description("Identifier")]  
    public int Id { get; set; }  
    public bool HasId => Id > 0;  
}  

Same for TextBox

public class TextBoxCustom : TextBox  
{  
    [Category("Behavior"), Description("Identifier")]  
    public int Id { get; set; }  
    public bool HasId => Id > 0;  
}  

The Id property may be set in code

checkBoxCustom1.Id = 12;  

Or in the property window

The default value is 0 although you can set the default value. If left as 0 a check can be done to see if it's been set.

if (textBoxCustom1.HasId)  
{  
    MessageBox.Show($"Id is {textBoxCustom1.Id}");  
}  
else  
{  
    MessageBox.Show("No id set for text box, press OK to set");  
    textBoxCustom1.Id = 1;  
}  

Alternately, Id can be nullable int thus a minor change.

public class CheckBoxCustom : CheckBox  
{  
    [Category("Behavior"), Description("Identifier")]  
    public int? Id { get; set; }  
    public bool HasId => Id.HasValue;  
}  

Still works the same.

if (checkBoxCustom1.HasId)  
{  
    MessageBox.Show($"Id is {checkBoxCustom1.Id}");  
}  
else  
{  
    MessageBox.Show("No id");  
}  

In closing in the above code HasId will show in the property window (unwanted) so that can be handled and also to show other types can be used I added a do nothing per-say Comment property.

public class CheckBoxCustom : CheckBox  
{  
    [Category("Behavior"), Description("Identifier")]  
    public int? Id { get; set; }  
    [Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]  
    public bool HasId => Id.HasValue;  
    [Category("Behavior"), Description("Comment")]  
    public string Comment { get; set; }  
}  

Answer 3

First option, write a component which implements IExtenderProvider e.g. this sample I had for another question. Add to a form and each control has Custom1 property in the control property window. Here it's a string but you can use any type, also this is for all controls, you might only want specific type of controls.

using System.Collections;  
using System.ComponentModel;  
using System.Windows.Forms;  
  
namespace ExtenderSample  
{  
    [ProvideProperty("Custom1", typeof(Control))]  
    public class ControlExtender : Component, IExtenderProvider  
    {  
        private Hashtable _controls = new Hashtable();  
        public bool CanExtend(object extendee)  
        {  
            return extendee is Control;  
        }  
  
        public string GetCustom1(Control control)  
        {  
            if (_controls.ContainsKey(control))  
            {  
                return (string)_controls[control];  
            }  
  
            return null;  
        }  
        public void SetCustom1(Control control, string value)  
        {  
            if (string.IsNullOrWhiteSpace(value))  
            {  
                _controls.Remove(control);  
            }  
            else  
            {  
                _controls[control] = value;  
            }  
        }  
    }  
  
}  
  

MessageBox.Show(controlExtender1.GetCustom1(textBox1));  

Otherwise a extension method e.g.

public static class Extensions  
{  
    public static int Identifier(this TextBox sender)  
    {  
        if (sender.Tag is null)  
        {  
            return -1;  
        }  
        else  
        {  
            if (int.TryParse(sender.Tag.ToString(), out var value))  
            {  
                return value;  
            }  
            else  
            {  
                return -1;  
            }  
        }  
    }  
}  

Usage

var id = textBox1.Identifier();  
if (id > -1)  
{  
      
}