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POUpdate Graph while picking values from the database
 

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    <p>I am trying to <strong>pick values from the database and keep updating the graph from there</strong>. Using <a href="https://stackoverflow.com/questions/661561/how-to-update-the-gui-from-another-thread-in-c/661662#661662">How to update the GUI from another thread in C#?</a> my code is:</p> <pre><code>private void button1_Click(object sender, EventArgs e) { string myConnection = "datasource=localhost;port=3306;username=root;password=root"; MySqlConnection conDataBase = new MySqlConnection(myConnection); MySqlCommand cmdDataBase = new MySqlCommand(" select * from data.test; ", conDataBase); MySqlDataReader myReader; this.Invoke((MethodInvoker)delegate { try { conDataBase.Open(); myReader = cmdDataBase.ExecuteReader(); while (myReader.Read()) { this.chart1.Series["Series1"].Points.AddXY(myReader.GetString("datetime"), myReader.GetInt32("temp")); } conDataBase.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } }); } </code></pre> <p>Though i do not get any error, i dont think its working as the graph is constant/static. Any suggestions. <strong>What i basically want is that this graph keeps updating based on the new values in the database...something like a heart beat monitor or to that effect.</strong> </p> <p>Any suggestions...Regards</p> <p>Edit: I also tried using background worker but there also i get the following on button click:</p> <pre><code>Cross thread operation not valid: Control 'charTemperature' accessed from athread other than the thread it was created on </code></pre> <p>The code:</p> <pre><code>using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using MySql.Data.MySqlClient; using System.Threading; namespace project { public partial class Form2 : Form { private BackgroundWorker bw = new BackgroundWorker(); public Form2() { InitializeComponent(); bw.WorkerSupportsCancellation = true; bw.WorkerReportsProgress = false; bw.DoWork += new DoWorkEventHandler(bw_DoWork); } private void btnExit_Click(object sender, EventArgs e) { Application.Exit(); } private void btnTemperature_Click(object sender, EventArgs e) { if (bw.IsBusy != true) { bw.RunWorkerAsync(); } //this.Invoke((MethodInvoker)delegate // { /* string myConnection = "datasource=localhost;port=3306;username=root;password=root"; MySqlConnection conDataBase = new MySqlConnection(myConnection); MySqlCommand cmdDataBase = new MySqlCommand(" select * from data.test; ", conDataBase); MySqlDataReader myReader; try { conDataBase.Open(); myReader = cmdDataBase.ExecuteReader(); while (myReader.Read()) { this.chartTemperature.Series["Temperature"].Points.AddXY(myReader.GetString("datetime"), myReader.GetInt32("temp")); } conDataBase.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } //});*/ } private void btnStopUpdating_Click(object sender, EventArgs e) { if (bw.WorkerSupportsCancellation == true) { bw.CancelAsync(); } } private void bw_DoWork(object sender, DoWorkEventArgs e) { BackgroundWorker worker = sender as BackgroundWorker; while (true) { if ((worker.CancellationPending == true)) { e.Cancel = true; break; } else { string myConnection = "datasource=localhost;port=3306;username=root;password=root"; MySqlConnection conDataBase = new MySqlConnection(myConnection); MySqlCommand cmdDataBase = new MySqlCommand(" select * from data.test; ", conDataBase); MySqlDataReader myReader; try { conDataBase.Open(); myReader = cmdDataBase.ExecuteReader(); while (myReader.Read()) { this.chartTemperature.Series["Temperature"].Points.AddXY(myReader.GetString("datetime"), myReader.GetInt32("temp")); System.Threading.Thread.Sleep(1000); } conDataBase.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } } } } private void Form2_Load(object sender, EventArgs e) { } } } </code></pre> <p>One more futile attempt...nothing happens on button click...</p> <pre><code>using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using MySql.Data.MySqlClient; using System.Threading; namespace project { public partial class Form2 : Form { private BackgroundWorker bw = new BackgroundWorker(); public string vdatetime; public Int32 vtemp; public Form2() { InitializeComponent(); bw.WorkerSupportsCancellation = true; // bw.WorkerReportsProgress = false; bw.DoWork += new DoWorkEventHandler(bw_DoWork); } private void btnExit_Click(object sender, EventArgs e) { Application.Exit(); } private void btnTemperature_Click(object sender, EventArgs e) { //if (bw.IsBusy != true) //{ this.bw.RunWorkerAsync(); //} //this.Invoke((MethodInvoker)delegate // { /* string myConnection = "datasource=localhost;port=3306;username=root;password=root"; MySqlConnection conDataBase = new MySqlConnection(myConnection); MySqlCommand cmdDataBase = new MySqlCommand(" select * from data.test; ", conDataBase); MySqlDataReader myReader; try { conDataBase.Open(); myReader = cmdDataBase.ExecuteReader(); while (myReader.Read()) { this.chartTemperature.Series["Temperature"].Points.AddXY(myReader.GetString("datetime"), myReader.GetInt32("temp")); } conDataBase.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } //});*/ } private void btnStopUpdating_Click(object sender, EventArgs e) { // if (bw.WorkerSupportsCancellation == true) //{ this.bw.CancelAsync(); //} } private void bw_DoWork(object sender, DoWorkEventArgs e) { BackgroundWorker worker = sender as BackgroundWorker; if ((worker.CancellationPending == true)) { e.Cancel = true; //break; } else { string myConnection = "datasource=localhost;port=3306;username=root;password=root"; MySqlConnection conDataBase = new MySqlConnection(myConnection); MySqlCommand cmdDataBase = new MySqlCommand(" select * from data.test; ", conDataBase); MySqlDataReader myReader; try { conDataBase.Open(); myReader = cmdDataBase.ExecuteReader(); //this.Invoke((MethodInvoker)delegate //{ while (myReader.Read()) { vdatetime = myReader.GetString("datetime"); vtemp = myReader.GetInt32("temp"); //Thread.Sleep(300); // this.chartTemperature.Series["Temperature"].Points.AddXY(myReader.GetString("datetime"), myReader.GetInt32("temp")); // System.Threading.Thread.Sleep(1000); } conDataBase.Close(); // }); } catch (Exception ex) { MessageBox.Show(ex.Message); } } } private void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e) { if (e.Cancelled) { // The user canceled the operation. MessageBox.Show("Operation was canceled"); } else if (e.Error != null) { // There was an error during the operation. string msg = String.Format("An error occurred: {0}", e.Error.Message); MessageBox.Show(msg); } else { this.chartTemperature.Series["Temperature"].Points.AddXY(vdatetime, vtemp); } } private void Form2_Load(object sender, EventArgs e) { } } } </code></pre>
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