Solved

Help with C# mult threaded sql binding

Posted on 2011-02-23
1
485 Views
Last Modified: 2012-05-11
My goal with this program is create a class that accepts three arguments (sql statement, datagridview, db connection) and then executes the SQL command on another thread. I am having an issue when it comes to invoking the data grid. Shown below is my code.

namespace multThreadDB
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        NpgsqlConnection conn = new NpgsqlConnection();
       
        private void button1_Click(object sender, EventArgs e)
        {
            db1 d = new db1("select * from meter;", dataGridView1, conn);
            new Thread(new ThreadStart(d.fillGrid)).Start();
        }
    }

    public class db1
    {
        string sql;
        DataGridView grid;
        NpgsqlConnection conn;
        DataSet ds = new DataSet();
       

        public db1(string sql, DataGridView grid, NpgsqlConnection conn)
        {
            this.grid = grid;
            this.sql = sql;
            this.conn = conn;
        }

        public void fillGrid()
        {
            conn.Open();
            NpgsqlDataAdapter adapter = new NpgsqlDataAdapter(sql, conn);
            adapter.Fill(ds);
            SetResult(ds);
            conn.Close();
        }

        delegate void SetDataSetDelegate(DataSet parameter);

        void SetResult(DataSet ds)
        {
            try
            {
                if (!InvokeRequired)
                    grid.DataSource = ds.Tables[0];
                else
                    Invoke(new SetDataSetDelegate(SetResult), new object[] { ds });
            }
            catch { }
        }
    }
}

I receiving errors on the invoke lines. It seems the error is caused because i am invoking a control from another class? How can I fix this?

Thanks in advance!
0
Comment
Question by:j4jones
1 Comment
 
LVL 23

Accepted Solution

by:
wdosanjos earned 250 total points
ID: 34962869
UI controls can only be accessed from the UI Thread.  If you try to access it from a worker thread an exception is thrown.  I think that's what's happening.

Instead of the Thread class I suggest that you use the BackgroundWorker class, which already provide the necessary support.

More about BackgroundWorker:
http://msdn.microsoft.com/en-us/library/8xs8549b.aspx
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Article by: Ivo
C# And Nullable Types Since 2.0 C# has Nullable(T) Generic Structure. The idea behind is to allow value type objects to have null values just like reference types have. This concerns scenarios where not all data sources have values (like a databa…
We all know that functional code is the leg that any good program stands on when it comes right down to it, however, if your program lacks a good user interface your product may not have the appeal needed to keep your customers happy. This issue can…
When you create an app prototype with Adobe XD, you can insert system screens -- sharing or Control Center, for example -- with just a few clicks. This video shows you how. You can take the full course on Experts Exchange at http://bit.ly/XDcourse.
With Secure Portal Encryption, the recipient is sent a link to their email address directing them to the email laundry delivery page. From there, the recipient will be required to enter a user name and password to enter the page. Once the recipient …

914 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

16 Experts available now in Live!

Get 1:1 Help Now