QHttp Problem

[musaulker]

Hello,

I want to add checkLatestVersion functionality to my program. My program will connect foo.com/bar.file and get the latestVersion and compares with currentVersion. If latestVersion is greater then currentVersion that it will give a message (there is a new version, download it) and then quit.

Here is my code:

void VersionChecker::checkVersion()
{
	versionHttp = new QHttp();
	connect(versionHttp,SIGNAL(requestFinished(int,bool)),this,SLOT(versionHttpData(int,bool)));
	versionHttp>setHost("www.foo.com", 80);
	versionHttpRequestId = versionHttp->get("/bar/latest.txt");
}
 
void VersionChecker::versionHttpData(int id, bool error)
{
	if (id != versionHttpRequestId)
	{
		return;
	}
	if(error)
	{
		latestVersionString = "2.0.0.0";
		return;
	}
	latestVersionString = versionHttp->readAll();
}
 
QString VersionChecker::getLatestVersion()
{
	return latestVersionString;
}

void VersionChecker::checkVersion()
{
	versionHttp = new QHttp();
	connect(versionHttp,SIGNAL(requestFinished(int,bool)),this,SLOT(versionHttpData(int,bool)));
	versionHttp>setHost("www.foo.com", 80);
	versionHttpRequestId = versionHttp->get("/bar/latest.txt");
}

void VersionChecker::versionHttpData(int id, bool error)
{
	if (id != versionHttpRequestId)
	{
		return;
	}
	if(error)
	{
		latestVersionString = "2.0.0.0";
		return;
	}
	latestVersionString = versionHttp->readAll();
}

QString VersionChecker::getLatestVersion()
{
	return latestVersionString;
}

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and how i use it:

QApplication a(argc, argv);
 
	VersionChecker *versionControl = new VersionChecker();
	versionControl->checkVersion();
	QString latestVersion = versionControl->getLatestVersion();
 
	if(latestVersion != _PROGRAM_VERSION)
	{
		NewVersionAvailableDialog *newVersionDialog = new NewVersionAvailableDialog();
		newVersionDialog->setModal(true);
		newVersionDialog->setAttribute( Qt::WA_DeleteOnClose );
		newVersionDialog->show();
		return a.exec();
	}
 
 
	MainForm w;
	w.show();
	a.connect(&a, SIGNAL(lastWindowClosed()), &a, SLOT(quit()));
	return a.exec();

QApplication a(argc, argv);

	VersionChecker *versionControl = new VersionChecker();
	versionControl->checkVersion();
	QString latestVersion = versionControl->getLatestVersion();

	if(latestVersion != _PROGRAM_VERSION)
	{
		NewVersionAvailableDialog *newVersionDialog = new NewVersionAvailableDialog();
		newVersionDialog->setModal(true);
		newVersionDialog->setAttribute( Qt::WA_DeleteOnClose );
		newVersionDialog->show();
		return a.exec();
	}


	MainForm w;
	w.show();
	a.connect(&a, SIGNAL(lastWindowClosed()), &a, SLOT(quit()));
	return a.exec();

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The problem is, the program runs, QHttp connects and gets the latest version but, while these are being MainWindow is shown. I dont want it to be shown. Firstly latestVersion control must be finished. If current version is the latest version, then MainWindow must shown, otherwise i want the program to quit.

How can I do that? Where's the problem?

[jacek]

QHttp needs time and a running event loop to fetch the results. You can try:

versionControl->checkVersion();
QCoreApplication::processEvents();
QString latestVersion = versionControl->getLatestVersion();

versionControl->checkVersion();
QCoreApplication::processEvents();
QString latestVersion = versionControl->getLatestVersion();

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You can also change VersionChecker a bit and make it show either the main window or NewVersionAvailableDialog. In such case your code will look like this:

int main( int argc, char **argv )
{
   QApplication app(argc, argv);
 
   VersionChecker checker;
   checker->checkVersion();
 
   return app.exec();
}
...
void VersionChecker::runningOldVersion()
{
   NewVersionAvailableDialog dlg;
   dlg.exec();
}
...
void VersionChecker::runningNewestVersion()
{
    MainForm *mf = new MainForm();
    mf->setAttribute( Qt::WA_DeleteOnClose );
    mf->show();
}
...

int main( int argc, char **argv )
{
   QApplication app(argc, argv);

   VersionChecker checker;
   checker->checkVersion();
 
   return app.exec();
}
...
void VersionChecker::runningOldVersion()
{
   NewVersionAvailableDialog dlg;
   dlg.exec();
}
...
void VersionChecker::runningNewestVersion()
{
    MainForm *mf = new MainForm();
    mf->setAttribute( Qt::WA_DeleteOnClose );
    mf->show();
}
...

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[musaulker]

Ok I solved like in your second solution. Thanks for help

[musaulker]

But now there exists another problem. I have a firewall. Each time after i compile my program, firewall asks me permission for accessing internet. I say yes. No problem, it works sucessfully. But when i say no, the program still tries to connect to my server. It waits xx seconds (or minutes).

1- How can I solve it?
2- Is there a timeout mechanism for QHttp?
3- What should be if no firewall but slow internet connection?

[jacek]

2- Is there a timeout mechanism for QHttp?

Yes, it is, but it's well hidden. You can create an ordinary socket and set a timeout using setsockopt(), next you'll need to wrap it in a QTcpSocket and use QHttp::setSocket().

It would be nice, if there was some Qt-way to change socket options, but so far I haven't seen any.

1- How can I solve it?

As a workaround you can make your own timeout mechanism using QTimer.