On each grid update the dropdownlist on the page appends an additional list of items

Question

This is quite funny and I do not understand what is happening. I have a radgrid on an asp.net page and a dropdownlist completely independent from the grid (at least this is my impression).

This is the dropdownlist and the full code I have in pageLoad:

protected void Page_Load(object sender, EventArgs e)
{
    if (Session["IsLogin"] == null)
    {
        Response.Redirect("Default.aspx");
    }


    SqlConnection con = new SqlConnection(strConnString);
    con.Open();
    str = "select * from Pagamenti ORDER BY [Data] DESC";
    com = new SqlCommand(str, con);
    sqlda = new SqlDataAdapter(com);
    ds = new DataSet();
    sqlda.Fill(ds, "Pagamenti");
    string spacer = "   --|--   ";
    for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
    {
        DropDownList1.Items.Add(string.Format("{0:Id ####}", ds.Tables[0].Rows[i]["Id"]) +
            spacer + Convert.ToDateTime(ds.Tables[0].Rows[i]["Data"]).ToString("dd/MM/yyyy") +
            spacer + string.Format("{0:R #.###,##}", (ds.Tables[0].Rows[i]["Somma"])));
    }
    con.Close();
}

Every time I make an operation that updates the grid (insert, delete, update, refresh) an additional list of items is added to the dropdownlist. So on a fresh page I have 50 items, after an update of the grid they became 100 and so on. I do I solve this problem?

Answer 1

Wrap your dropdown code in if(!IsPostBack){...}

Answer 2

Check if its an update with

if(!IsPostback)
{
//yourcodehere
}

or delete it everytime. But better take care about the ASP.NET lifecycle. (You should allways check for PostBack!) A postback occurs if the client does a action which sends a request to the server.