如何使用本身的选定值更改数据网格视图组合框列的默认值

Question

i have a data grid view combo box column in my data grid view. On on load event of form i am loading the companies name in combo box column and through cell formatting event i am giving the default value to data grid view combo box column.

Now if i select different value from combo box column it does not get reflected. means only default value is there.

My code for on load and cell formatting is

   public void dataGridView1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
    {
        SqlConnection c = new SqlConnection();
        c.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename='D:\\Documents\\Visual Studio 2008\\Projects\\Accounts\\Accounts\\Database1.mdf';Integrated Security=True;User Instance=True";
        c.Open();

        if (e.ColumnIndex == 1 && Viewcashvoucher.mk != "")
        {
            string mky = Viewcashvoucher.mk;
                 string q = "select * from lgr where main_key ='" + mky + "'";
                 SqlCommand cmd = new SqlCommand(q, c);
        SqlDataReader dr = cmd.ExecuteReader();

        if (dr.Read())
        {
            e.Value = dr["account_n"].ToString();

        }
        }
        c.Close();
    }

and on load event is

private void Cash_Voucher_Load(object sender, EventArgs e)
    {
        string mky = Viewcashvoucher.mk;
        SqlConnection c = new SqlConnection();
        c.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename='D:\\Documents\\Visual Studio 2008\\Projects\\Accounts\\Accounts\\Database1.mdf';Integrated Security=True;User Instance=True";
        c.Open();


            string q = "select max(date) from lgr ";
            SqlCommand cmd = new SqlCommand(q, c);
            SqlDataReader rd = cmd.ExecuteReader();
            try
            {
                if (rd.Read())
                {
                    DateTime date = rd.GetDateTime(0);
                    if (date != null)
                    {
                        tbdate.Text = date.ToShortDateString();
                    }
                }
            }
            catch (Exception ex)
            {
                tbdate.Text = DateTime.Now.ToShortDateString();
            }
            c.Close();
            c.Open();
            string q1 = "select account_n from master";
            SqlCommand cmd1 = new SqlCommand(q1, c);
            SqlDataReader rd1 = cmd1.ExecuteReader();
            DataGridViewComboBoxColumn acname = dataGridView1.Columns[1] as DataGridViewComboBoxColumn;
            while (rd1.Read())
            {
                acname.Items.Add(Convert.ToString(rd1["account_n"]));


            }

}

actually i am using same data grid view for insert and update operation. i want that as user select different value from combo box list the default value should be replaced by selected one.

thanks in advance...

Answer 1

CellFormatting event handler is not the right place to set the default value. CellFormatting occurs whenever the content of the cells needs to be formated for display. Whenever you the change the value in the combobox and accept the value, this event is raised and the default value code resets the user selection.

In DataGridView.RowsAdded you could set the defalut value for the combobox cell for the newly added row(s)

Sample Code:

void dataGridView1_RowsAdded(object sender, DataGridViewRowsAddedEventArgs e)
    {
        for (int i = e.RowIndex; i < (e.RowIndex+e.RowCount); i++)
        {
            dataGridView1.Rows[i].Cells[comboboxcolumn_index].Value = defaultvalue;
        }            
    }

Answer 2

you can also bind the DataBindingComplete event. The only difference in previous and this answer is @Junaith bind the RowAdded event mean it will call the function every time you add the row. and here in mycase I bound DataBindingComplete event which will fire after the grid is full loaded mean this will call only once and that time it will check the all the checkbox in first column of the grid for all the lines.

mygrid.DataBindingComplete +=
       new DataGridViewBindingCompleteEventHandler(mygrid_DataBindingComplete);

then and you have to define a function name as mygrid_DataBindingComplete

    private void mygrid_DataBindingComplete(object sender, DataGridViewBindingCompleteEventArgs e)
    {
        DataGridView temp = (DataGridView)sender;

        foreach (DataGridViewRow rw in temp.Rows)
        {
            // here 0 indicating the checbox column is the first column in grid
            // first column so index would be 0.  true will check the checkbox
            rw.Cells[0].Value = true;
        }
     }

Answer 3

hai you can Just use this on RowAdded Event or DataGridview comboboxcolumn creation time. It will Set the Default Value

comboboxcolumn_Name.DefaultCellStyle.NullValue = "Please Select";

Answer 4

void dataGridView1_RowsAdded(object sender, DataGridViewRowsAddedEventArgs e)
{
    for (int i = e.RowIndex; i < (e.RowIndex+e.RowCount); i++)
    {
        comboboxcolumn_Name.DefaultCellStyle.NullValue = "Please Select";
    }
}