Cant edit dataGridView cell value programmatically

Question

I am making an error handelder, it will activate when i type in an invalid time or date format like 12:456 and 55-32-1986. Then the program should change the cell value back to the prev value.

I am using .NET 4.5 and this is a winforms application

The code:

dataGridView2.DataError += dataGridView2_DataError;

private void dataGridView2_DataError(object sender, DataGridViewDataErrorEventArgs anError)
{
    // MessageBox.Show("Error happened " + anError.Context.ToString());

    if (anError.Context == DataGridViewDataErrorContexts.Commit)
    {
        MessageBox.Show("Commit error");
    }

    if (anError.Context == DataGridViewDataErrorContexts.CurrentCellChange)
    {
        MessageBox.Show("Cell change");
    }

    if (anError.Context == DataGridViewDataErrorContexts.Parsing)
    {
        MessageBox.Show("parsing error");
    }

    if (anError.Context == DataGridViewDataErrorContexts.LeaveControl)
    {
        MessageBox.Show("leave control error");
    }

    if ((anError.Exception) is ConstraintException)
    {
        DataGridView view = (DataGridView)sender;
        view.Rows[anError.RowIndex].ErrorText = "an error";
        view.Rows[anError.RowIndex].Cells[anError.ColumnIndex].ErrorText = "an error";

        anError.ThrowException = false;
    }

    if ((anError.Exception) is FormatException)
    {
        if (dataGridView2.CurrentCell == dataGridView2.CurrentRow.Cells[3])
        {
            MessageBox.Show("Please enter a valid time value" + prevTime);
            dataGridView2.CurrentCell.Value = prevTime;
            dataGridView2.EndEdit();
        }
        if (dataGridView2.CurrentCell == dataGridView2.CurrentRow.Cells[2])
        {
            MessageBox.Show("Please enter a valid date");
            dataGridView2.CurrentCell.Value = prevDate;
            dataGridView2.EndEdit();
        }
    }

    //cell types
    d.Tables.Add(booking);
        booking.Columns.Add("nr.", typeof(int));
        booking.Columns.Add("Name", typeof(string));
        booking.Columns.Add("Date", typeof(DateTime));
        booking.Columns.Add("Time", typeof(DateTime));

    //Datasource
    dataGridView2.DataSource = booking;
}

prevDate- and TimeValue are declared at datagrid_onBeginEdit so that i have the values.

I have the prev values. The code runs from start to end. But from row 2 and afterwards, it wont change the value of the cells programmatically. I can only do it manualy, and when the code cant change the value, then the error messagebox keeps on appearing. The datagridview is not read only.

Cells: nr. / Name / Date / Time

Any help will be appreciated, thanks in advance.

EDIT: I added the full code of the event handeler

PS. If i am unclear somewhere, or if you need more information then just tell whats needed.

Answer 1

You don't need to save prevDate and prevTime yourself, I've tried restoring the values but it seems that we can't change them (I'm still excited to find out how to change them in that context). But I have the best solution here for you, we just need to use the method CancelEdit() of the DataGridView and it should be what you want although it doesn't show how to change the cell values in the context described in your question. Here is the code:

if ((anError.Exception) is FormatException)
{
    if (dataGridView2.CurrentCell == dataGridView2.CurrentRow.Cells[3])
    {
        MessageBox.Show("Please enter a valid time value" + prevTime);
        dataGridView2.CancelEdit();//Only this works
    }
    if (dataGridView2.CurrentCell == dataGridView2.CurrentRow.Cells[2])
    {
        MessageBox.Show("Please enter a valid date");
        dataGridView2.CancelEdit();//Only this works
    }
}

I hope it helps, again, I'm still excited about how to change the cell values in that context. If I find how to do it, I'll post it as another answer for you. Thanks!