Question

I am trying to fetch values on a GridView with the following code:

protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
    GridViewRow row = GridView1.SelectedRow;
    string Username = row.Cells[3].Text;
    string Password = row.Cells[4].Text;
    string Email = row.Cells[5].Text;
    string ID_Inscricao = row.Cells[1].Text;
    SqlConnection sqlConn = new SqlConnection(
        ConfigurationManager.ConnectionStrings["FormacaoConnectionString"].ToString());
    SqlCommand sqlComm = new SqlCommand();

    sqlComm = sqlConn.CreateCommand();
    sqlComm.Parameters.Add("@Username", SqlDbType.Text);
    sqlComm.Parameters.Add("@Password", SqlDbType.Text);
    sqlComm.Parameters.Add("@Email", SqlDbType.Text);
    sqlComm.Parameters.Add("@ID_Inscricao", SqlDbType.Text);

    sqlComm.Parameters["@Username"].Value = Username;
    sqlComm.Parameters["@Password"].Value = Password;
    sqlComm.Parameters["@Email"].Value = Email;
    sqlComm.Parameters["@ID_Inscricao"].Value = ID_Inscricao;
    string sql = "INSERT INTO Utilizadores " +
        "(Username, Password, Email,ID_Inscricao) " +
        "VALUES (@Username, @Password, @Email, @ID_Inscricao)";
    sqlComm.CommandText = sql;
    sqlConn.Open();
    sqlComm.ExecuteNonQuery();
    sqlConn.Close();
}

So, the problem is I can’t get the values from the GridView, but instead get a “NullReferenceException was unhandled by user code”. Can anybody tell me what I’m doing wrong?

Best regards

Answer 1

Each line which looks like this:

sqlComm.Parameters["@Username"].Value = Username;

Requires that parameter to actually exist on the command object, but you’ve commented those lines out. Put back in one of these:

sqlComm.Parameters.Add("@Username", SqlDbType.Text);

For every parameter you’re setting the value for.

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Edited after comment

Based on the fact that this line causes a NullReferenceException:

string Username = row.Cells[3].Text;

I can say for cetain that either

a) row is null – there is no SelectedRow in your grid
b) row.Cells is null, the selected row has no cells
c) row.Cells[3] is null, the selected row has cells, but there is no cell 4(cells is zero based)

There is no way of helping you further than that, You should set a breakpoint on the line that is failing and inspect each of the 3 cases above to see which one is null