How can you access a reader in another class in ASP.Net

Question

I have a DataClassLibrary I use for the connectionString and then I also have the C# code behind the ASP page. I want to be able to use While(reader.read()) in my ASP page so that I can get the multiple values the reader returns. How can I go about implementing this? I have provided the code below for my Data Class and the ASP page.

Data Class:

reader = DBHelper.executeQuery(dbConn, sqlString.ToString(), parameters);
        if (reader != null)
        {
            if (reader.Read())
            {
                OrderID = (int)Convert.ToInt32(reader["OrderID"]);
                CaseNum6 = (int)Convert.ToInt32(reader["CaseNum6"]);
                CaseNum9 = (int)Convert.ToInt32(reader["CaseNum9"]);
                Group = (int)Convert.ToInt32(reader["Group"]);
                Completed = (bool)reader["Completed"];
            }
            else
                throw new Exception("No record returned");
            reader.Close();
            reader.Dispose();
            dbConn.Close();
            dbConn.Dispose();
        }
    }
    catch (Exception ex)
    {
        throw ex;
    }
    finally
    {
        if (dbConn != null)
        {
            try { dbConn.Close(); dbConn.Dispose(); }
            catch { }
         }
        if (reader != null)
        {
            try { reader.Close(); reader.Dispose(); }
            catch { }
        }
    }

ASP page to implement on:

LineAData NewDataA = new LineAData();
LineAData NewDataB = new LineAData();
string connString = ConfigurationManager.ConnectionStrings["Connection"].ConnectionString;

protected void Page_Load(object sender, EventArgs e)
{

    NewDataA.load(1,3);
    NewDataB.load(2,3);

    L1.Text = NewDataA.CaseNum6.ToString();
    L2.Text = NewDataA.CaseNum9.ToString();
    L7.Text = NewDataA.CaseNum6.ToString();
    L8.Text = NewDataA.CaseNum9.ToString();

    L4.Text = NewDataB.CaseNum6.ToString();
    L5.Text = NewDataB.CaseNum9.ToString();
    L10.Text = NewDataB.CaseNum6.ToString();
    L11.Text = NewDataB.CaseNum9.ToString();
}

Answer 1

I did not understand your question well, but as far as i understood. I think you require the multiple values from the reader on your asp page. If this is the requirement then what you can do is, just create one class which will contain all the column name which will be there in the reader.

The method which is there in your DataClassLibrary will return the List.

The below example will help you:

public class User
    {
    public long nUser { get; set; }

    public string cUserID { get; set; }

    public string cName { get; set; }

    public string cPassword { get; set; }
}

 public class cUser
 {
public List<User> GetUsers()
    {
        try
        {
            SqlConnection connection = new SqlConnection(ConnectionString);

            command = new SqlCommand(connection);
            command.CommandType = CommandType.Text;

            List<User> tuserList = new List<User>();

            User tuser = null;

            connection.Open();

            reader = command.ExecuteReader();

            while (reader.Read())
            {
                tuser = new User();

                tuser.nUser = long.Parse(reader["nUser"].ToString());
                tuser.cUserID = reader["cUserID"].ToString();
                tuser.cName = reader["cName"].ToString();
                tuser.cPassword = reader["cPassword"].ToString();

                tuserList.Add(tuser);
            }

            return tuserList;

        }

        catch (SqlException ex)
        {
            return null;
        }

        catch (Exception ex)
        {
            return null;
        }

        finally
        {
            if (reader != null)
            {
                reader.Close();
            }

            if (connection != null)
            {
                connection.Close();
            }
        }

    }
  }

On ASPX page:

just create the object of the class in which this method is there. and get it. Suppose it is there in the cUser class.

    cUser a = new cUser();

    var list = a.GetUsers();

I hope it will help you.. :)

Answer 2

With some tweaks to your DBHelper, you could return the reader from your data (access) class to your web page code-behind, however, you will need to leave the connection open when returning it to the web page code behind, and instead, execute the reader with the option CommandBehavior.CloseConnection which will close the connection when the page closes the reader.

Dal

public IDataReader ExecuteReaderMethod()
{
   // Set up conn and command 
   // ...
   return command.ExecuteReader(CommandBehavior.CloseConnection);
}

ASP Code Behind

using (var reader = MyDal.ExecuteReaderMethod())
{
   while (reader.Read())
   {
       someUIControl.Text = reader.GetString("OrderID");
   }
}

To be honest though, since it seems you need to render the whole page anyway, there probably isn't much point in getting the lazy evaluation benefit of the reader. You might be better off just converting the result to a DataSet or a List<> of custom entities in your DAL and returning this to your web page, and then release the precious DB resources early.