在C＃Windows窗体中将组和项添加到ListView

Question

I'm trying to create a ListView in Windows Form that contains groups and items i get from DataBase.

My ListView is called "lstItems"

In the begining, the ListView is empty and I fill it with data during the runnig of the program.

This is the code I use to create the groups:

foreach(DataRow r in tasksTbl.Rows)
{
    string groupName = "group" + num;
    num++;
    lstItems.Groups.Add(groupName, r.Field<string>(0));
}

The tasksTbl table is not empty and it creates several group that I cannot see on the screen at this point.

This is the code I use to create the items and subItems for the groups:

private void CreateItem(DataTable tbl)
{
    int taskId = tbl.Rows[0].Field<int>(0);
    string taskName = tbl.Rows[0].Field<string>(1);
    DateTime startDate = tbl.Rows[0].Field<DateTime>(2);
    DateTime endDate = tbl.Rows[0].Field<DateTime>(3);

    string dateStr = startDate.ToString() + " - " + endDate.ToString();

    ListViewItem item = new ListViewItem(dateStr);
    item.Tag = taskId.ToString();

    foreach (DataRow r in tbl.Rows)
    {
        string position = r.Field<string>(5);
        string soldier = r.Field<string>(6);
        item.SubItems.Add(soldier + " (" + position + ")");
    }

    foreach(ListViewGroup grp in lstItems.Groups)
        if (grp.Header.Equals(taskName))
            grp.Items.Add(item);
}

Here also the tbl table is not empty and it creates the items and sub items to each group.

I can see in the debugger that the groups has the items properly.

My problem is that I cannot see the groups or the items on the screen.

What am I missing?

Can someone give me a hand?

Thank you in advance!

Answer 1

itzick,

You need to create the groups as you go and assign them to the items you add to the ListView Control. Here is a simple example which loads a ListView with the numbers 65 to 76. The groups are based upon the number modulus 5.

Create a form, add a ListView called listView1, add the method below and call that method during form load. You should see a ListView with five groups and a few member items in each group.

    private void LoadListView()
    {
        // Assume we are in a form, with a ListView control called listView1 on the form

        // Create a group label array
        var groupLabels = new string[5];
        groupLabels[0] = "aaa";
        groupLabels[1] = "bbb";
        groupLabels[2] = "ccc";
        groupLabels[3] = "ddd";
        groupLabels[4] = "eee";

        for (var i = 65; i < 76; i++)
        {
            // Find group or create a new group
            ListViewGroup lvg = null;
            var found = false;
            foreach (var grp in listView1.Groups.Cast<ListViewGroup>().Where(grp => grp.ToString() == groupLabels[i % 5]))
            {
                found = true;
                lvg = grp;
                break;
            }

            if (!found)
            {
                // Group not found, create
                lvg = new ListViewGroup(groupLabels[i % 5]);
                listView1.Groups.Add(lvg);
            }

            // Add ListViewItem
            listView1.Items.Add(new ListViewItem {Text = i.ToString(CultureInfo.InvariantCulture), Group = lvg});
        }

Answer 2

I figured out my problem.

I needed to add columns to the ListView and then, to add the items to the ListView and only in the end to add the items to the groups.

I did it and now it works.