Question

I’m having strange issues with the check box control in C# .Net
My code below shows all logic that is required – _itemsChecked is a private dictionary containing all of the _fixtures and whether they are true or false (checked or un checked)

What I want is to be able to search my check list whilst retaining those which have been checked previously. If a checked item is included in the search results I want it to be checked.

The code nearly works! But for some reason boxes are randomly checked here and there, and it appears to work through debug but when the screen returns to the control it then hasn’t worked.

Sure I’m missing something very simple.

My logic is:

DataSource includes those which match the typed search query,
Iterate through this list and check if the Guid is true in the dictionary.
If it is true then we set it as checked.

Hope I have provided adequate information.

Many thanks in advance.

 private void searchTextBox_KeyUp(object sender, EventArgs e)
        {
            lst.DataSource = _fixtures
                .OrderBy(f => 
                    f.Description)
                .Where(f => 
                    f.Description.ToLower().Contains(searchFixturesTextBox.Text.ToLower()))
                .ToList();

            lst.DisplayMember = "Description";

            for (var i = 0; i < lst.Items.Count; i++)
                if(_itemsChecked.Contains(new KeyValuePair<Guid, bool>(((Fixture)lst.Items[i]).Guid, true)))
                    lst.SetItemChecked(i, true);
        }

        void lst_ItemCheck(object sender, ItemCheckEventArgs e)
        {
            var selectedItem = ((ListBox) sender).SelectedItem as Fixture;

            if (selectedFixtureItem != null)
                _itemsChecked[selectedItem.Guid] = e.CurrentValue == CheckState.Unchecked;
        }

Answer 1

So I put this together from a few examples I found. The majority of the work came from How do I make a ListBox refresh its item text?

public class Employee
{
   public string Name { get; set; }
   public int Id { get; set; }
   public bool IsChecked { get; set; }

   public override string ToString()
   {
      return Name;
   }
}

public partial class Form1 : Form
{
   // Keep a bindable list of employees
   private BindingList<Employee> _employees;

   public Form1()
   {
      InitializeComponent();
      // Load some fake employees on load
      this.Load += new EventHandler(Form1_Load);
      // Click once to trigger checkbox changes
      checkedListBox1.CheckOnClick = true;
      // Look for item check change events (to update there check property)
      checkedListBox1.ItemCheck += 
         new ItemCheckEventHandler(CheckedListBox_ItemCheck);
   }

   // Load some fake data
   private void Form1_Load(object sender, EventArgs e)
   {
      _employees = new BindingList<Employee>();
      for (int i = 0; i < 10; i++)
      {
         _employees.Add(new Employee() 
            { Id = i, Name = "Employee " + i.ToString() });
      }

      // Display member doesnt seem to work, so using ToString override instead
      //checkedListBox1.DisplayMember = "Name";
      //checkedListBox1.ValueMember = "Name";
      checkedListBox1.DataSource = _employees;

      // Another example databind to show selection changes
      txtId.DataBindings.Add("Text", _employees, "Id");
      txtName.DataBindings.Add("Text", _employees, "Name");
   }

   // Item check changed, update the Employee IsChecked property
   private void CheckedListBox_ItemCheck(object sender, ItemCheckEventArgs e)
   {
      CheckedListBox clb = sender as CheckedListBox;
      if (clb != null)
      {
         Employee checked_employee = clb.Items[e.Index] as Employee;
         if (checked_employee != null)
         {
            checked_employee.IsChecked = (e.NewValue == CheckState.Checked);
         }
      }
   }

   // Just a simple test that removes an item from the list, rebinds it
   // and updates the selected values
   private void btnChangeList_Click(object sender, EventArgs e)
   {
      _employees.RemoveAt(1);
      checkedListBox1.DataSource = _employees;

      for (var i = 0; i < checkedListBox1.Items.Count; i++)
      {
         Employee employee_to_check = checkedListBox1.Items[i] as Employee;
         if (employee_to_check != null)
         {
            checkedListBox1.SetItemChecked(i, employee_to_check.IsChecked);
         }
      }
   }
}