Programmatically Checking DataBound CheckListBox

Question

I have a DataBound "CheckedListBox", I need to check some items on it. I tried with following code...

if (!string.IsNullOrEmpty(search.Languages))
        {
            string[] langs = search.Languages.Split(',');
            for (int i = 0; i < (langs.Length - 1); i++)
            {
                for (int j = 0; j < clbLang.Items.Count; j++)
                {
                    string lng = clbLang.Items[j] as string;
                    if (lng.Trim() == langs[i])
                    {
                        clbLang.SetItemChecked(j, true);
                        break;
                    }
                }
            }
        }

No errors, debuged execution is going through "checking" process, but finally I cannot see anything checked on it.

Then I have added a button and added following code to it. (upon click check all the items)

private void button9_Click(object sender, EventArgs e)
    {
        for (int i = 0; i < clbLang.Items.Count; i++)
        {
            clbLang.SetItemChecked(i, true);
        }
    }

It is "checking" all the items, Please tell me if anyone can see a issue here...?

Answer 1

Finally found out, it is a Bug introduced by MS.

It is well explained here.

The issue is easy to reproduce. Just hide and show a databound CheckedListBox and you will notice how the previously checked items get unchecked.

CheckedListBox SetItemChecked method not working

So we have to find a workaround... I tried follwing way, it is working nice...

At the place where I was calling checking of items I have added following... I am adding what I need to check in Tag of the control.

if (!string.IsNullOrEmpty(search.Languages))
{
    clbLang.Tag = search.Languages;
}

Then, following code in that control's "VisibleChanged()" event.

private void clbLang_VisibleChanged(object sender, EventArgs e)
    {
        string lngs = clbLang.Tag as string;
        if (!string.IsNullOrEmpty(lngs))
        {
            string[] langs = lngs.Split(',');
            foreach (string lang in langs)
            {
                int j = 0;
                foreach (DataRowView row in clbLang.Items)
                {
                    if (row != null)
                    {
                        string lng = row[1] as string;
                        if (lng.Trim() == lang)
                        {
                            clbLang.SetItemChecked(j, true);
                            break;
                        }
                    }
                    j++;
                }
            }
        }
    }

This works well with me, hope it will benefit you...