How to handle event of combobox in datagridview?

Question

I have a checkbox[All] and a datagridview as below:

I would like:

• The inside datagridview, if all checkbox is checked, the checkbox[All] is checked and otherwise if all checkbox is unchecked, the checkbox[All] is unchecked
• The inside datagridview, there is a checkbox that is unchecked, the checkbox[All] is unchecked

I tried it but I am not able to do it:

private void dataGridView_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
    bool isAllCheck = false;

    if (e.ColumnIndex == 0)
    {
        foreach (DataGridViewRow row in dataGridView.Rows)
        {
            DataGridViewCheckBoxCell chk = row.Cells[0] as DataGridViewCheckBoxCell;

            isAllCheck = Convert.ToBoolean(chk.Value);
            if (!isAllCheck)
            {
                break;
            }
        }

        if (chkAllItem.Checked && !isAllCheck)
        {
            chkAllItem.Checked = false;
        }

        if (!chkAllItem.Checked && isAllCheck)
        {
            chkAllItem.Checked = true;
        }
    }
}

private void dataGridView_CurrentCellDirtyStateChanged(object sender, EventArgs e)
{
    if (this.dataGridView.IsCurrentCellDirty)
    {
        this.dataGridView.CommitEdit(DataGridViewDataErrorContexts.Commit);
    }
}

Any tips on these will be great help. Thanks in advance.

Answer 1

Setting the TrueValue, FalseValue and IndeterminateValue is a good start.

I found that I also need to do a bit more for this to work; in addition to your CurrentCellDirtyStateChanged event I also coded these:

This sets all CheckBoxCells:

private void cbx_all_CheckedChanged(object sender, EventArgs e)
{
    if (cbx_all.Tag == null) for (int i = 0; i < dataGridView.RowCount; i++)
    {
        dataGridView.Tag = "busy";
        dataGridView[yourCheckBoxcolumnIndex, i].Value = cbx_all.Checked;
        dataGridView.Tag = null;
    }
}

I coded the CellValueChanged instead of the CellContentClick event:

private void dataGridView_CellValueChanged(object sender, DataGridViewCellEventArgs e)
{
    if (e.ColumnIndex == yourCheckBoxcolumnIndex &&  dataGridView.Tag == null)
    {
       cbx_all.Tag = "busy";
       cbx_all.Checked = testChecks(e.ColumnIndex);
       cbx_all.Tag = null;
    }
}

I used the Tag property of the DGV and the CheckBox as a flag, that I am busy changing values by code. Some other means to avoid an endless-loop are just as fine.

This is the test function:

bool testChecks(int index)
{
    for (int r = 0; r < dataGridView.RowCount; r++)
        if  ( !(bool)dataGridView[index, r].Value ) return false;
    return true;
}