Compare the cell values of the selected checkboxes in DataGridView

Question

I have a DataGridView and Checkbox column attached to it. I would like to achieve something like this, when a few checkboxes are selected, it will compare the cells value of column named Description between those selected row. If the values are not same, a message box will be show up, else the value will be parse into a textbox.

As in example above, a messagebox should be show up when those rows are selected.

This is what i have done so far and i don't know how to continue from here.

private void datagridview1_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            foreach (DataGridViewRow r in datagridview1.Rows)
            {
                bool ckboxselected = !Convert.ToBoolean(r.Cells[0].Value);

                if (e.RowIndex >= 0 && e.ColumnIndex == 0)
                {
                    if (ckboxselected)
                    {
                        //compare
                    }
                    else
                    {
                        //another action
                    }
                }
            }
        }

I appreciate you help!

Answer 1

The CellClick event is raised when you mouse-click anywhere within the cell's bounds including the CheckBox area of the DataGridViewCheckBoxCell. Also, it's raised when you press the Space key while a content cell has focus. On the other hand, the CellContentClick event is raised when a content area (i.e. CheckBox) is hit by mouse or key and the cell's Value is about to change.

As I understand your question, you need to implement the latter to take an action if you get different descriptions (column 2) of the checked rows. If so, a simple LINQ query will do.

private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
    if (e.RowIndex >= 0 && e.ColumnIndex == 0)
    {
        // To get the new value...
        dataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit);

        var row = dataGridView1.Rows[e.RowIndex];
        var any = dataGridView1.Rows.Cast<DataGridViewRow>().Where(
            r => r.Index != row.Index && (bool)r.Cells[0].FormattedValue).Any(
            r => r.Cells[2].Value?.ToString().ToLower() != row.Cells[2].Value?.ToString().ToLower());

        if (any)
        {
            // Uncomment if you need to cancel the check...
            //row.Cells[0].Value = false;
            //dataGridView1.EndEdit();
            MessageBox.Show("Not same descriptions...");
        }
        else
        {
            // ...
        }
    }
}

If you need to skip the null descriptions.

private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
    if (e.RowIndex >= 0 && e.ColumnIndex == 0)
    {
        dataGridView1.CommitEdit(DataGridViewDataErrorContexts.Commit);

        var row = dataGridView1.Rows[e.RowIndex];

        if (row.Cells[2].Value == null) return;

        var any = dataGridView1.Rows.Cast<DataGridViewRow>().Where(
            r => r.Index != row.Index && (bool)r.Cells[0].FormattedValue && r.Cells[2].Value != null).Any(
            r => r.Cells[2].Value.ToString().ToLower() != row.Cells[2].Value.ToString().ToLower());

        if (any)
        {
            // Uncomment if you need to uncheck...
            //row.Cells[0].Value = false;
            //dataGridView1.EndEdit();
            MessageBox.Show("Not same descriptions...");
        }
        else
        {
            // ...
        }
    }
}

Trim .ToLower() calls for the case-sensitive comparisons.