QHttp related

[whoops.slo]

I have set a function that goes through the database. from it it collect url's and download the files. at some url's i get a response "Host XYZ not found" and the function does not work anymore (the function is called from a loop that goes from the first record to the last) - the QHttp get() does not work any more. the function start workiing again if i start it manually from button on the GUI. What is the difference betwet calling a function from the loop and from the GUI?
Regards;
Luka

[jacek]

What is the difference betwet calling a function from the loop and from the GUI?

None, if you have a single thread. Maybe there's something wrong with your application's logic? How many QHttp objects do you have?

[whoops.slo]

Here is the code of the app.:

void polje::skoci() {
 
	int i = 0;
	bool bOk;
	QString str = ui.t_1->text();
	int st = str.toInt(&bOk) + 1;
 
//write new number into textfield t_1
	ui.t_1->setText(QString::number(st));
 
//define http path = in this example i'm using static URL, in the real case
//it is collected from database
//the URL below is the one making problems... <=host not found since it does not exist, but the loop end and I can not start it
	QUrl urlt("http://www.anabanana.brb/");
 
//the URL below has corect host address, but the file is missing - responseHeader code 404
//	QUrl urlt("http://www.bubi.si/luka.html");
//the URL below is correct, just to test if the app. work
//	QUrl urlt("http://www.google.com/");
 
//define the path to the file into which we will write the contend of the page
	QDir pot(qApp->applicationDirPath());
	if(!pot.exists("html")) {
		pot.mkdir("html");
	}
	file = new QFile("html/blog_" + QString::number(st) + ".html");
	if (!file->open(QIODevice::WriteOnly)) {
		QMessageBox::critical(this, "Napaka", "Ne morem odpreti datoteke.");
		delete file;
		return;
	}
 
//open the connection and download the content of the page
//into the file specified
	http->setHost(urlt.host());
	httpGetId = http->get(urlt.path(), file);
 
}
 
void polje::httpRequestFinished(int requestId, bool error) {
 
	if (requestId != httpGetId)
		return;
 
//we close the specific file
	file->close();
 
	if (error) {
		//insert the error string into textfield t_2
		//just to find out what the error is
		ui.t_2->insertPlainText("\n" + ui.t_1->text() + ": " + http->errorString());
	}
	else {
		bool bOk;
		QString str = ui.t_1->text();
		int st = str.toInt(&bOk) + 1;
		if (st <= 10) {
			skoci();
		}
	}
}
 
void polje::readResponseHeader(const QHttpResponseHeader &responseHeader) {
 
	ui.t_2->insertPlainText("\n" + ui.t_1->text() + ": " + QString::number(responseHeader.statusCode()));
 
}

void polje::skoci() {

	int i = 0;
	bool bOk;
	QString str = ui.t_1->text();
	int st = str.toInt(&bOk) + 1;

//write new number into textfield t_1
	ui.t_1->setText(QString::number(st));

//define http path = in this example i'm using static URL, in the real case
//it is collected from database
//the URL below is the one making problems... <=host not found since it does not exist, but the loop end and I can not start it
	QUrl urlt("http://www.anabanana.brb/");

//the URL below has corect host address, but the file is missing - responseHeader code 404
//	QUrl urlt("http://www.bubi.si/luka.html");
//the URL below is correct, just to test if the app. work
//	QUrl urlt("http://www.google.com/");

//define the path to the file into which we will write the contend of the page
	QDir pot(qApp->applicationDirPath());
	if(!pot.exists("html")) {
		pot.mkdir("html");
	}
	file = new QFile("html/blog_" + QString::number(st) + ".html");
	if (!file->open(QIODevice::WriteOnly)) {
		QMessageBox::critical(this, "Napaka", "Ne morem odpreti datoteke.");
		delete file;
		return;
	}

//open the connection and download the content of the page
//into the file specified
	http->setHost(urlt.host());
	httpGetId = http->get(urlt.path(), file);

}

void polje::httpRequestFinished(int requestId, bool error) {

	if (requestId != httpGetId)
		return;

//we close the specific file
	file->close();

	if (error) {
		//insert the error string into textfield t_2
		//just to find out what the error is
		ui.t_2->insertPlainText("\n" + ui.t_1->text() + ": " + http->errorString());
	}
	else {
		bool bOk;
		QString str = ui.t_1->text();
		int st = str.toInt(&bOk) + 1;
		if (st <= 10) {
			skoci();
		}
	}
}

void polje::readResponseHeader(const QHttpResponseHeader &responseHeader) {

	ui.t_2->insertPlainText("\n" + ui.t_1->text() + ": " + QString::number(responseHeader.statusCode()));

}

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I have defined QHttp and the rest of undefined variables in the header file in the private section:

QHttp *http;
	QFile *file;
	int httpGetId;

QHttp *http;
	QFile *file;
	int httpGetId;

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Can anybody find the explanation and perhaps even the solution? Thank you!

Regards;
Luka

[jacek]

Well... I don't see any loop here. Anyway in case of an error you land here:

if (error) {
    //insert the error string into textfield t_2
    //just to find out what the error is
    ui.t_2->insertPlainText("\n" + ui.t_1->text() + ": " + http->errorString());
}

if (error) {
    //insert the error string into textfield t_2
    //just to find out what the error is
    ui.t_2->insertPlainText("\n" + ui.t_1->text() + ": " + http->errorString());
}

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Could you explain what do you want to do then? What do you mean by "the loop end and I can not start it"?

One more thing: IMO it would be better to change:

if (st <= 10) {
    skoci();
}

if (st <= 10) {
    skoci();
}

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to

if (st <= 10) {
    QTimer::singleShot( 0, this, SLOT( skoci() ) );
}

if (st <= 10) {
    QTimer::singleShot( 0, this, SLOT( skoci() ) );
}

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This way QHttp will have time to clean up itself after emitting requestFinished() signal.

[whoops.slo]

thanks for noticing that. it was my mistake, when i rewrite the code to make it clearer and to show just where my problem is i forgot to insert a lass to skoci() function...

if (error) {
		//insert the error string into textfield t_2
		//just to find out what the error is
		ui.t_2->insertPlainText("\n" + ui.t_1->text() + ": " + http->errorString());
		skoci();
	}
	else {
		bool bOk;
		QString str = ui.t_1->text();
		int st = str.toInt(&bOk) + 1;
		if (st <= 10) {
			skoci();
		}
	}

if (error) {
		//insert the error string into textfield t_2
		//just to find out what the error is
		ui.t_2->insertPlainText("\n" + ui.t_1->text() + ": " + http->errorString());
		skoci();
	}
	else {
		bool bOk;
		QString str = ui.t_1->text();
		int st = str.toInt(&bOk) + 1;
		if (st <= 10) {
			skoci();
		}
	}

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As far as I understand QHttp mechanism (am a beginner at it) when a get() is finished a requestFinished() signal is send. I have connected requestFinished() with httpRequestFinished() and responseHeaderReceived() with readResponseHeader()... Therefor when get() finish the httpRequestFinished() is called. At that point I call again the function skoci() and repeat this 10 times. It works with second and third URL (responseHeaderRecieved codes 404 and 200, but with the first one I do not get a responseHeaderReceived() since the host does not exist. In return I get an error, but when I try to call skoci() function from that error I call it but the get() is not called again...
Timer::SingleShot() does not work in this contect - the second time the function skoci() is not called!
There is obiously something wrong with my aproach to this problem, but I can not find where I made a mistake...

Regards, Luka

[jacek]

It works with second and third URL (responseHeaderRecieved codes 404 and 200, but with the first one I do not get a responseHeaderReceived() since the host does not exist. In return I get an error, but when I try to call skoci() function from that error I call it but the get() is not called again...

Do you change the host after the error has occured?

Add this at the beginning of httpRequestFinished():

qDebug() << httpGetId << requestId << error;

qDebug() << httpGetId << requestId << error;

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and this at the end of skoci():

qDebug() << urlt.host() << httpGetId;

qDebug() << urlt.host() << httpGetId;

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to see what's happening (don't forget about #include <QtDebug>).

Timer::SingleShot() does not work in this contect - the second time the function skoci() is not called!

Is that skoci() method a slot? Anyway you can forget about QTimer as QHttp is reentrant, so you can safely invoke setHost() and get() whenever you want.

[whoops.slo]

skoci() is not a slot - at least it was not meant to be...

I try what you suggest - qDebbug(). I am using Win XP, CodeBlock, MinGW and GDB and am new with debbugers. Therefor I can not understand what I should read from it (perhaps I have some setting set incorrectly). If you or somebody else have time and will to teach me how to set debbuger in this enviroment I would be most greatefull, since than I could at least look into what my app. is actually working

Thanks anyway for your help, I hope you can help me further, but if it is a lost case than... I will understand

Regards,
Luka

[jacek]

skoci() is not a slot - at least it was not meant to be...

That explains why the trick with QTimer didn't work.

I am using Win XP, CodeBlock, MinGW and GDB and am new with debbugers. Therefor I can not understand what I should read from it

Under windows you must add "CONFIG += console" to your .pro file to see the qDebug() output. Although debugger should be able to intercept these messages without it. Unfortunately I don't do much development under windows, so I can't help you with it.

[whoops.slo]

I was not able to get anything from the debugger. Instead I put requested strigns to be send to the textbox. This is the response I got from using host, that do not exist:

2
2, 1
2, 2
1: Host www.anabanana.brb not found
5

And this is from the one that exist (The "loop" run 5 times):

2
2, 1
1: 200
2, 2
4
4, 3
2: 200
4, 4
6
6, 5
3: 200
6, 6
8
8, 7
4: 200
8, 8
10
10, 9
5: 200
10, 10

I put the line below at the end of the skoci():

ui.t_2->insertPlainText("\n" + QString::number(httpGetId));

ui.t_2->insertPlainText("\n" + QString::number(httpGetId));

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and the line below at the beggining of httpRequestFinished():

ui.t_2->insertPlainText("\n" + QString::number(httpGetId) + ", " + QString::number(requestId));

ui.t_2->insertPlainText("\n" + QString::number(httpGetId) + ", " + QString::number(requestId));

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Can this help?
Regards, Luka

[jacek]

What happens when you change skoci() like this?

http->setHost( "localhost" ); // added
http->setHost( urlt.host() );
httpGetId = http->get( urlt.path(), file );

http->setHost( "localhost" ); // added
http->setHost( urlt.host() );
httpGetId = http->get( urlt.path(), file );

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[whoops.slo]

I get the same responce:

3
3, 1
3, 2
3, 3
6

I'll try something else... Before I call GET() I will check for ERROR(). If ERROR() is HostNotFound than GET() will not be called...