Rows cannot be programmatically added to the datagridview rows collection when the control is data-bound

Question

I'm new winform C#.So now i have some problem when I trying add row to datagridview

public void SourceForDataGridView(string str)
    {
        try
        {
            SqlDataAdapter da = new SqlDataAdapter(str, cnn);
            DataTable dt = new DataTable();
            da.Fill(dt);
            BindingSource bSource = new BindingSource();
            bSource.DataSource = dt;
            dataGridView1.DataSource = bSource;
            da.Update(dt);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

That's my source for datagridview1,

SourceForDataGridView("SELECT TenThuoc,DVTinh,SL,DONGIA,THANHTIEN,HSD FROM CTNHAPTHUOC JOIN THUOC ON CTNHAPTHUOC.MaThuoc = Thuoc.MaThuoc JOIN NHAPTHUOC ON NHAPTHUOC.MANHAPTHUOC = CTNHAPTHUOC.MANHAPTHUOC WHERE CTNHAPTHUOC.MaNhapThuoc = '" + txtMaPNT.Text.Trim() + "' ");

I want to try add newRow when click a button with value from datagridview2

            double sum = 0;
            sum = double.Parse(txtDGMua.Text.Trim().ToString()) * double.Parse(txtSLMua.Text.Trim().ToString());
            bool existed = false;
            for (int i = 0; i < dataGridView1.Rows.Count; i++)
            {
                int selectedrowindex = dataGridView2.SelectedCells[0].RowIndex;
                DataGridViewRow selectedRow = dataGridView2.Rows[selectedrowindex];
                string a = Convert.ToString(selectedRow.Cells[0].Value);
                string b = Convert.ToString(dataGridView1.Rows[i].Cells[0].Value);
                if (a == b)
                {
                    existed = true;
                    dataGridView1.Rows[i].Cells[2].Value = int.Parse(dataGridView1.Rows[i].Cells[2].Value.ToString()) + int.Parse(txtSLMua.Text);
                    //sum += (double.Parse(txtDGMua.Text.Trim().ToString())*double.Parse(txtSLMua.Text.Trim().ToString()));
                    dataGridView1.Rows[i].Cells[4].Value = double.Parse(dataGridView1.Rows[i].Cells[2].Value.ToString()) * double.Parse(dataGridView1.Rows[i].Cells[3].Value.ToString());
                    break;
                }
            }
            if (!existed)
            {
                try
                {
                    //object[] item = { this.dataGridView2.CurrentRow.Cells[0].Value.ToString(), this.dataGridView2.CurrentRow.Cells[1].Value.ToString(), txtSLMua.Text, txtDGMua.Text, sum, dTPHSD.Value };
                    this.dataGridView1.Rows.Add(this.dataGridView2.CurrentRow.Cells[0].Value.ToString(), this.dataGridView2.CurrentRow.Cells[1].Value.ToString(), txtSLMua.Text, txtDGMua.Text, sum, dTPHSD.Value);
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.Message);
                }
            }

but , if(!exists) , this's not working. Please help me.

In addition to correcting the sql-injection-prone select ( [see bobby Tables!!](https://xkcd.com/327/) ), the usual way is to add to the DataSource dt.. — TaW, Jun 13 '15 at 10:42

score 1 · Accepted Answer · answered Jun 13 '15 at 10:44

1

Instead of inserting a DataGridViewRow try to insert a DataRow to your DataSource like this

var dataSource = dataGridView1.DataSource as BindingSource;
var dataTable = dataSource.DataSource as DataTable;

dataTable.Rows.Add(value1, value2,...)

this will update your BindingSource and show the new values of the DataTable.

answered Jun 13 '15 at 10:44

stefankmitph

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Thank, It's working :D :D – long hoangvan Jun 13 '15 at 10:59
System.NullReferenceException: 'Object reference not set to an instance of an object.' This is frustrating as I am having to do a winforms app and haven't done one in 15 years. – Tom Stickel Feb 21 '22 at 06:59

Rows cannot be programmatically added to the datagridview rows collection when the control is data-bound

1 Answers1