Qt QNetworkAccessManager and Slot not working - c++

Question

i am a beginner in c++ and i am trying to retrieve data from a website using http request and to download the data in a file .
I am using the classes :
QMainWindow
QtNetwork/QNetworkAccessManager
QtNetwork/QNetworkRequest
QtNetwork/QNetworkReply
QUrl
The thing is that the file is created but there is no data in the file and i am getting an error that i don't understand . I searched through the forum found some similar kind of problems but did not understand as i am a beginner . Please help me its a school project and i am really stuck here.
Here is the httpWindow.h code
#ifndef HTTPWINDOW_H
#define HTTPWINDOW_H
#include <QMainWindow>
#include <QtNetwork/QNetworkAccessManager>
#include <QtNetwork/QNetworkRequest>
#include <QtNetwork/QNetworkReply>
#include <QUrl>
#include <QString>
class QFile;
namespace Ui {
class httpWindow;
}
class httpWindow : public QMainWindow
{
Q_OBJECT
public:
explicit httpWindow(QWidget *parent = 0);
~httpWindow();
void request(QUrl url);
private slots:
void downloadFile();
void httpFinished();
void httpReadyRead();
private:
Ui::httpWindow *ui;
QUrl url;
QNetworkAccessManager *manager;
QNetworkRequest requete;
QNetworkReply *reply;
QFile *file;
int httpGetId;
bool httpRequestAborted;
};
#endif // HTTPWINDOW_H
Here is the httpwindow.cpp
#include <QtWidgets>
#include <qnetwork.h>
#include <QString>
#include "httpwindow.h"
#include "ui_httpwindow.h"
httpWindow::httpWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::httpWindow)
{
ui->setupUi(this);
downloadFile();
}
httpWindow::~httpWindow()
{
delete ui;
}
void httpWindow::request(QUrl url)
{
manager = new QNetworkAccessManager(this);
connect(manager, SIGNAL(finished()),
this, SLOT(httpFinished()));
//requete.setUrl(QUrl("http://fxrates.fr.forexprostools.com/index.php?force_lang=5&pairs_ids=1;3;2;4;7;5;8;6;&header-text-color=%23FFFFFF&curr-name-color=%230059b0&inner-text-color=%23000000&green-text-color=%232A8215&green-background=%23B7F4C2&red-text-color=%23DC0001&red-background=%23FFE2E2&inner-border-color=%23CBCBCB&border-color=%23cbcbcb&bg1=%23F6F6F6&bg2=%23ffffff&bid=show&ask=show&last=show&change=hide&last_update=hide"));
requete.setUrl(url);
reply = manager->get(requete);
connect(reply, SIGNAL(&reply::readyRead()), this, SLOT(httpReadyRead()));
}
void httpWindow::downloadFile()
{
QMessageBox msg ;
QUrl url("http://fxrates.fr.forexprostools.com/index.php?force_lang=5&pairs_ids=1;3;2;4;7;5;8;6;&header-text-color=%23FFFFFF&curr-name-color=%230059b0&inner-text-color=%23000000&green-text-color=%232A8215&green-background=%23B7F4C2&red-text-color=%23DC0001&red-background=%23FFE2E2&inner-border-color=%23CBCBCB&border-color=%23cbcbcb&bg1=%23F6F6F6&bg2=%23ffffff&bid=show&ask=show&last=show&change=hide&last_update=hide") ;
qDebug() << url.toString();
QFileInfo fileInfo(url.path());
//msg.setText("fileInfo = " + fileInfo);
QString fileName = "C:\\testQt\\" + fileInfo.fileName();
msg.setText("fileName = " + fileName);
if (fileName.isEmpty()){
fileName = "C:\testQt\fichier.html";
msg.setText(" création d'un nouveau fichier fichier.html ");
}
if (QFile::exists(fileName)) {
QFile::remove(fileName);
return;
}
file = new QFile(fileName);
msg.setText(" QFile::exists(fileName) == true , file : ");
if (!file->open(QIODevice::WriteOnly)) {
delete file;
file = 0;
return;
}
// schedule the request
httpRequestAborted = false;
request(url);
}
void httpWindow::httpFinished()
{
if (httpRequestAborted) {
if (file) {
file->close();
file->remove();
delete file;
file = 0;
}
reply->deleteLater();
return;
}
file->flush();
file->close();
QVariant redirectionTarget = reply->attribute(QNetworkRequest::RedirectionTargetAttribute);
if (reply->error()) {
file->remove();
// QMessageBox::information(this, tr("HTTP"),
// tr("Download failed: %1.")
// .arg(reply->errorString()));
// downloadButton->setEnabled(true);
} else if (!redirectionTarget.isNull()) {
QUrl newUrl = url.resolved(redirectionTarget.toUrl());
// if (QMessageBox::question(this, tr("HTTP"),
// tr("Redirect to %1 ?").arg(newUrl.toString()),
// QMessageBox::Yes | QMessageBox::No) == QMessageBox::Yes) {
url = newUrl;
reply->deleteLater();
file->open(QIODevice::WriteOnly);
file->resize(0);
request(url);
return;
}
reply->deleteLater();
reply = 0;
delete file;
file = 0;
}
void httpWindow::httpReadyRead()
{
// this slot gets called every time the QNetworkReply has new data.
// We read all of its new data and write it into the file.
// That way we use less RAM than when reading it at the finished()
// signal of the QNetworkReply
if (file)
file->write(reply->readAll());
}
Here is the main.cpp code
#include "httpwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
httpWindow w;
w.show();
return a.exec();
}
The errors :
can't find linker symbol for virtual table for `QMessageBox' value
found `RGB_MASK' instead
can't find linker symbol for virtual table for `QMessageBox' value
found `RGB_MASK' instead
"http://fxrates.fr.forexprostools.com/index.php?force_lang=5&pairs_ids=1;3;2;4;7;5;8;6;&header-text-color=%23FFFFFF&curr-name-color=%230059b0&inner-text-color=%23000000&green-text-color=%232A8215&green-background=%23B7F4C2&red-text-color=%23DC0001&red-background=%23FFE2E2&inner-border-color=%23CBCBCB&border-color=%23cbcbcb&bg1=%23F6F6F6&bg2=%23ffffff&bid=show&ask=show&last=show&change=hide&last_update=hide"
QObject::connect: No such signal QNetworkAccessManager::finished() in ..\ppe3_trading_test\httpwindow.cpp:24
QObject::connect: (receiver name: 'httpWindow')
QObject::connect: No such signal QNetworkReplyHttpImpl::&reply::readyRead() in ..\ppe3_trading_test\httpwindow.cpp:31
QObject::connect: (receiver name: 'httpWindow')
Please do help me its really important for my schooling .

Answer 1

connect(reply, SIGNAL(&reply::readyRead()), this, SLOT(httpReadyRead()));
You're mixing up old syntax and new syntax, it should be
connect(reply, SIGNAL(readyRead()), this, SLOT(httpReadyRead()));
or better yet using new syntax(Qt5 only):
connect(reply, &QNetworkReply::readyRead, this, &httpWindow::httpReadyRead);
QNetworkAccessManager doesn't have a finished() signal it has a finished(QNetworkReply*) signal, read the docs.