Help with Listening for notifications

[Akiva]

So after working on it... I have it running without any errors... but I don't know if I am receiving any signals or not. My code has been updated~ If there are any errors, it is likely on line 56 of database.cpp. I just don't know if I am listening properly, or what.
mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
 
namespace Ui {
	class MainWindow;
}
 
class MainWindow : public QMainWindow
{
	Q_OBJECT
 
public:
	explicit MainWindow(QWidget *parent = 0);
	~MainWindow();
private:
	Ui::MainWindow *ui;
 
 
//Lobby Chat
private slots: void on_actionConnect_triggered();
private slots: void connect_to_lobby(QString s);
 
 
};
 
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
	class MainWindow;
}

class MainWindow : public QMainWindow
{
	Q_OBJECT

public:
	explicit MainWindow(QWidget *parent = 0);
	~MainWindow();
private:
	Ui::MainWindow *ui;


//Lobby Chat
private slots: void on_actionConnect_triggered();
private slots: void connect_to_lobby(QString s);


};

#endif // MAINWINDOW_H

To copy to clipboard, switch view to plain text mode 

database.h

#ifndef DATABASE_H
#define DATABASE_H
 
#include <QObject>
#include <QDebug>
#include <QtSql>
#include "mainwindow.h"
 
class database : public QObject
{
	Q_OBJECT
public:
	explicit database(QObject *parent = 0);
 
 
//Lobby Chat
public:  void connect_to_lobby(MainWindow *main);
private: QSqlDatabase db;
signals: void send_chat(QString);
private slots: void listen_for_notifications(QString);
private: MainWindow *mainprivate;
 
 
};
 
#endif // DATABASE_H

#ifndef DATABASE_H
#define DATABASE_H

#include <QObject>
#include <QDebug>
#include <QtSql>
#include "mainwindow.h"

class database : public QObject
{
	Q_OBJECT
public:
	explicit database(QObject *parent = 0);


//Lobby Chat
public:  void connect_to_lobby(MainWindow *main);
private: QSqlDatabase db;
signals: void send_chat(QString);
private slots: void listen_for_notifications(QString);
private: MainWindow *mainprivate;


};

#endif // DATABASE_H

To copy to clipboard, switch view to plain text mode 

database.cpp

#include "database.h"
 
database::database(QObject *parent) :
	QObject(parent)
{
 
}
 
void database::connect_to_lobby(MainWindow *main)
{
	mainprivate = main;
 
	qDebug() << "Adding Database Driver...";
	db = QSqlDatabase::addDatabase("QPSQL");
	qDebug() << "Setting Connection...";
	db.setHostName("135.0.189.14");
	qDebug() << "Setting Database...";
	db.setDatabaseName("dominionlinux");
	qDebug() << "Setting Username...";
	db.setUserName("player");
	qDebug() << "Setting Password...";
	db.setPassword("player");
 
	qDebug() << "Attempting to open Database";
	bool ok = db.open();
	if (ok == false){
		qDebug() << "Failed to connect to Lobby " << db.lastError();
	}
	else
	{
		qDebug() << "Success; Connected to Database as 'player'!";
		QSqlQuery query;
		// Select all the entries from the table "lobbychat", but only 25
		qDebug() << "Preparing Query...";
		query.prepare("SELECT * FROM lobbychat ORDER BY time asc LIMIT 25;");
		qDebug() << "Executing Query...";
		query.exec();
 
		//Set the initial lobby chat, getting history as far back as 25 lines
		qDebug() << "Grabbing lobby chat text...";
		connect(this,SIGNAL(send_chat(QString)),main,SLOT(connect_to_lobby(QString)));
		while (query.next())
		{
			QString name = query.value(0).toString();
			QString time = query.value(1).toString();
			QString chat = query.value(2).toString();
			QString s = QString("<font color='green'>" + name + "</font> <small>" + time + "</small> " + chat);
			emit send_chat(s);
		}
		qDebug() << "Success; The 25 most recent lines of chat have been grabbed and placed into chat";
 
		qDebug() << "Listening for chat from the database...";
		db.driver()->subscribeToNotification("lobbychat");
		qDebug() << "Attempting to listen for notifications...";
		connect(db.driver(),SIGNAL(notification(QString)), this, SLOT(listen_for_notifications(QString)));
		qDebug() << "unsure if it worked";
 
	}
}
 
void database::listen_for_notifications(QString snake)
{
	qDebug() << "Attempting to connect notifications to text browser";
	connect(this,SIGNAL(send_chat(QString)),mainprivate,SLOT(connect_to_lobby(QString)));
	qDebug() << "Attempting to emit notification";
	emit send_chat(snake);
}

#include "database.h"

database::database(QObject *parent) :
	QObject(parent)
{

}

void database::connect_to_lobby(MainWindow *main)
{
	mainprivate = main;

	qDebug() << "Adding Database Driver...";
	db = QSqlDatabase::addDatabase("QPSQL");
	qDebug() << "Setting Connection...";
	db.setHostName("135.0.189.14");
	qDebug() << "Setting Database...";
	db.setDatabaseName("dominionlinux");
	qDebug() << "Setting Username...";
	db.setUserName("player");
	qDebug() << "Setting Password...";
	db.setPassword("player");

	qDebug() << "Attempting to open Database";
	bool ok = db.open();
	if (ok == false){
		qDebug() << "Failed to connect to Lobby " << db.lastError();
	}
	else
	{
		qDebug() << "Success; Connected to Database as 'player'!";
		QSqlQuery query;
		// Select all the entries from the table "lobbychat", but only 25
		qDebug() << "Preparing Query...";
		query.prepare("SELECT * FROM lobbychat ORDER BY time asc LIMIT 25;");
		qDebug() << "Executing Query...";
		query.exec();

		//Set the initial lobby chat, getting history as far back as 25 lines
		qDebug() << "Grabbing lobby chat text...";
		connect(this,SIGNAL(send_chat(QString)),main,SLOT(connect_to_lobby(QString)));
		while (query.next())
		{
			QString name = query.value(0).toString();
			QString time = query.value(1).toString();
			QString chat = query.value(2).toString();
			QString s = QString("<font color='green'>" + name + "</font> <small>" + time + "</small> " + chat);
			emit send_chat(s);
		}
		qDebug() << "Success; The 25 most recent lines of chat have been grabbed and placed into chat";

		qDebug() << "Listening for chat from the database...";
		db.driver()->subscribeToNotification("lobbychat");
		qDebug() << "Attempting to listen for notifications...";
		connect(db.driver(),SIGNAL(notification(QString)), this, SLOT(listen_for_notifications(QString)));
		qDebug() << "unsure if it worked";

	}
}

void database::listen_for_notifications(QString snake)
{
	qDebug() << "Attempting to connect notifications to text browser";
	connect(this,SIGNAL(send_chat(QString)),mainprivate,SLOT(connect_to_lobby(QString)));
	qDebug() << "Attempting to emit notification";
	emit send_chat(snake);
}

To copy to clipboard, switch view to plain text mode 

mainwindow.cpp

#include "mainwindow.h"
#include "database.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
	QMainWindow(parent),
	ui(new Ui::MainWindow)
{
	ui->setupUi(this);
}
 
MainWindow::~MainWindow()
{
	delete ui;
}
 
void MainWindow::on_actionConnect_triggered()
{
	database db;
	db.connect_to_lobby(this);
}
void MainWindow::connect_to_lobby(QString s)
{
	ui->textBrowser->append(s);
}

#include "mainwindow.h"
#include "database.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
	QMainWindow(parent),
	ui(new Ui::MainWindow)
{
	ui->setupUi(this);
}

MainWindow::~MainWindow()
{
	delete ui;
}

void MainWindow::on_actionConnect_triggered()
{
	database db;
	db.connect_to_lobby(this);
}
void MainWindow::connect_to_lobby(QString s)
{
	ui->textBrowser->append(s);
}

To copy to clipboard, switch view to plain text mode 

Thanks ahead of time.

[ChrisW67]

You connect to the notification signal just like any other (Signals and slots),

connect(db.driver(), SIGNAL(notification(QString)), SLOT(myNotificationHandler(QString)));

connect(db.driver(), SIGNAL(notification(QString)), SLOT(myNotificationHandler(QString)));

To copy to clipboard, switch view to plain text mode 

BTW Googling found an example in this forum
http://www.qtcentre.org/threads/1072...ToNotification
And a general article on the topic
http://blog.qt.digia.com/blog/2007/1...notifications/

[Akiva]

HOW ?!!?!!?
Can I repay you?

I just don't understand why I couldnt get it to work, and yet... you, just beautifully solved all my woes, with one line of code .

Thank you

[Lesiok]

First of all definition of QSqlDriver::notification signal is

void notification( const QString & name )

void notification( const QString & name )

To copy to clipboard, switch view to plain text mode 

not

void notification( QString name )

void notification( QString name )

To copy to clipboard, switch view to plain text mode 

.

[anda_skoa]

First of all definition of QSqlDriver::notification signal is

void notification( const QString & name )

void notification( const QString & name )

To copy to clipboard, switch view to plain text mode 

not

void notification( QString name )

void notification( QString name )

To copy to clipboard, switch view to plain text mode 

.

Those two are equivalent as far as the connect() statement is concerned, so the connect is OK.

@Akiva: your database::listen_for_notifications() slot connects again and again, a connection that you already establish before in database::connect_to_lobby() (line 41 in your code snippet).
Unless listen_for_notification does need to something more than it currently does, you can simply connect the driver's signal to your own

connect(db.driver(), SIGNAL(notification(QString)), this, SIGNAL(send_chat(QString)));

connect(db.driver(), SIGNAL(notification(QString)), this, SIGNAL(send_chat(QString)));

To copy to clipboard, switch view to plain text mode 

Cheers,
_