有一个无效 SelectedValue，因为它不在项目列表中

有一个无效 SelectedValue，因为它不在项目列表中

这个错误让我头疼了很长时间，在网上也查找了很多方法，但对我来说好像不奏效。

找来找去，最后还是决定用笨方法来解决。

  protected void XX_DataBinding(object sender, EventArgs e)
    {

        DropDownList ddl = (DropDownList)sender;

        ddl.Items.Add("");

        CreateDDL("select dataValue from daiBasicData where dataClass='XX' ", ddl);

      
        DataRowView  dr = (DataRowView)DetailsView1.DataItem;
        int i = ddl.Items.IndexOf(ddl.Items.FindByValue(dr.Row["aField"].ToString()));
        if (i == -1) i = 0;
        ddl.SelectedValue = ddl.Items[i].Value;

    }

   private void CreateDDL(String sql, DropDownList ddl)
    {
        try
        {
            if (conn != null)
            {
                if (conn.State == ConnectionState.Open)
                {
                    SqlCommand comd = new SqlCommand();
                    comd.Connection = conn;
                    comd.CommandText = sql;
                    SqlDataReader reader = comd.ExecuteReader();
                    if (reader.HasRows)
                    {
                        while (reader.Read())
                        {
                            if (reader[0] != System.DBNull.Value)
                                ddl.Items.Add(reader[0].ToString());
                        }
                    }
                    reader.Close();
                    comd.Dispose();
                }
            }
        }
        catch (Exception ex)
        {
            Response.Write(ex.ToString());
        }
    }