I keep getting the following error in the browser 'Invalid attempt to read when no data is present.'

Question

Hi,

I'm new to .NET and trying to create a web application. I'm trying to query my database and read the results (only one row) into an SQLDataReader, then display them in a table on a web page. But when I do I keep getting the error below.

Invalid attempt to read when no data is present.

here's my code

        //draws a row of data in  the table
        public void drawDataRow(int itemID, int quantity)
        {
            int cost = 0;
            SqlDataReader rd = readFromDB(itemID);

            TableRow tr = new TableRow();

            TableCell tc1 = new TableCell();
            TableCell tc2 = new TableCell();
            TableCell tc3 = new TableCell();
            TableCell tc4 = new TableCell();
            TableCell tc5 = new TableCell();



                tc1.Controls.Add(new LiteralControl("" + rd.GetInt32(0)));
                tc2.Controls.Add(new LiteralControl("" + rd.GetString(1)));
                tc3.Controls.Add(new LiteralControl("" + quantity));
                tc4.Controls.Add(new LiteralControl("" + rd.GetInt32(2)));

                cost = rd.GetInt32(2) * quantity;//calculate cost

                bill += cost;//increment total bill

                tc1.Controls.Add(new LiteralControl("" + cost));

            //add cells to row
            tr.Cells.Add(tc1);
            tr.Cells.Add(tc2);
            tr.Cells.Add(tc3);
            tr.Cells.Add(tc4);
            tr.Cells.Add(tc5);

            //add row to table
            Contents.Rows.Add(tr);

        }//end drawDataRow

the above method calls the one below

       public SqlDataReader readFromDB(int itemID )
        {
            SqlConnection connect = new SqlConnection();
            
                //specify connection string
                connect.ConnectionString = ConfigurationManager.ConnectionStrings["connectionString"].ConnectionString;

                
                SqlCommand comm = new SqlCommand("get_row", connect);
                connect.Open();//open the connection

                //notify SQLCommand object that it will be using a procedure
                comm.CommandType = CommandType.StoredProcedure;
                comm.Parameters.Add( new SqlParameter("@itemID", itemID));//pass a parameter to the procedure
                SqlDataReader reader = comm.ExecuteReader(CommandBehavior.CloseConnection);


                return reader;

        }//end connectToDB

Any help is welcome, I'm at my wits end.

Thanx

Answer 1

I don't use the DataReader at all, but I've "played" with it in the past. I believe that you're missing the call to rd.Read(). I think that you need to put all your code in a while (rd.Read()) loop like this:

SqlDataReader rd = readFromDB(itemID);
while (rd.Read())
{
            TableRow tr = new TableRow();
            TableCell tc1 = new TableCell();
            TableCell tc2 = new TableCell();
            TableCell tc3 = new TableCell();
            TableCell tc4 = new TableCell();
            TableCell tc5 = new TableCell();
                tc1.Controls.Add(new LiteralControl("" + rd.GetInt32(0)));
                tc2.Controls.Add(new LiteralControl("" + rd.GetString(1)));
                tc3.Controls.Add(new LiteralControl("" + quantity));
                tc4.Controls.Add(new LiteralControl("" + rd.GetInt32(2)));
                cost = rd.GetInt32(2) * quantity;//calculate cost
                bill += cost;//increment total bill
                tc1.Controls.Add(new LiteralControl("" + cost));
            //add cells to row
            tr.Cells.Add(tc1);
            tr.Cells.Add(tc2);
            tr.Cells.Add(tc3);
            tr.Cells.Add(tc4);
            tr.Cells.Add(tc5);
            //add row to table
            Contents.Rows.Add(tr);
}

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~~Bonnie Berent DeWitt [C# MVP]

geek-goddess-bonnie.blogspot.com

Answer 2

It worked!!!!!!!!!  Thanx Geek Goddess :-))))))

Answer 3

You're welcome, Kalombo!!!! Glad I could help!!   Could you come back and mark my post as the answer?

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~~Bonnie Berent DeWitt [C# MVP]

geek-goddess-bonnie.blogspot.com