QNetworkRequest And signal/slots

[VidoX]

My code is:

#ifndef HTTPACTION_H
#define HTTPACTION_H

#include <QtNetwork>
#include <QNetworkAccessManager>
#include <QUrl>

class HttpAction : public QObject
{
    Q_OBJECT

public:
    HttpAction();
    void startRequest();
    void setUrl(QUrl url);


private slots:
    void httpFinished();

private:
    QUrl httpUrl;
    QNetworkAccessManager qnam;
    QNetworkReply *reply;
};

#endif

----------------------

HttpAction::HttpAction()
{
    
}

void HttpAction::startRequest()
{
    qWarning("2");
    reply = qnam.get(QNetworkRequest(httpUrl));

    connect(reply, SIGNAL(finished()), this, SLOT(httpFinished()));
}

void HttpAction::httpFinished()
{

     qWarning("3");

     if (reply->error() == QNetworkReply::NoError) {

         QByteArray bytes = reply->readAll();
     }

    reply->deleteLater();
}

void HttpAction::setUrl(QUrl url) {

    httpUrl = url;
}


--------------------

#include "httpaction.h"

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

}

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


void MainWindow::on_pushbutton_clicked()
{

    qWarning("1");

    HttpAction* http = new HttpAction;
    http->setUrl(QUrl("http://google.com"));
    http->startRequest();

    qWarning("4");

}

--------------

And output:
1
2
4
3

Why httpFinished() is executed after qWarning("4") ? I want to make http requests class to use everywhere in my app.

[rahul.kulshreshtha]

My code is:

And output:
1
2
4
3

Why httpFinished() is executed after qWarning("4") .

because qnam.get(.......) is asynchronous method which returns immediately after sending request to server. It does not wait for the response. When you make a request then it's state is managed by QNetworkAccessManager. so in your code; qnam is responsible for handling resonse; and you should connect qnam as below

 connect(qnam, SIGNAL(finished(QNetworkReply*)), this, SLOT(finishedSlot(QNetworkReply*)));

I am not sure why you are using reply instead of qnam.

As soon as qnam will get response from server. It will emit signal finished() and finishedSlot will be executed. Read more about signals, slots and asynchronous calls.

[VidoX]

Thanks, but changed to nam and it's the same

#ifndef HTTPACTION_H
#define HTTPACTION_H

#include <QtNetwork>
#include <QNetworkAccessManager>
#include <QUrl>

class HttpAction : public QObject
{
    Q_OBJECT

public:
    HttpAction();
    void startRequest();
    void setUrl(QUrl url);


private slots:
    void httpFinished(QNetworkReply* reply);

private:
    QUrl httpUrl;

};

#endif

----------------------

HttpAction::HttpAction()
{
    
}

void HttpAction::startRequest()
{
    qWarning("2");

    QNetworkAccessManager* nam;
    nam = new QNetworkAccessManager(this);

    connect(nam, SIGNAL(finished(QNetworkReply*)),
             this, SLOT(httpFinished(QNetworkReply*)));

    QNetworkReply* reply = nam->get(QNetworkRequest(httpUrl));

}

void HttpAction::httpFinished(QNetworkReply* reply)
{

     qWarning("3");

     if (reply->error() == QNetworkReply::NoError) {

         QByteArray bytes = reply->readAll();
     }

    reply->deleteLater();
}

void HttpAction::setUrl(QUrl url) {

    httpUrl = url;
}


--------------------

#include "httpaction.h"

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

}

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


void MainWindow::on_pushbutton_clicked()
{

    qWarning("1");

    HttpAction* http = new HttpAction;
    http->setUrl(QUrl("http://google.com"));
    http->startRequest();

    qWarning("4");

}

--------------

[VidoX]

Found a solution:

void HttpAction::startRequest()
{
    qWarning("2");

    QNetworkAccessManager* nam;
    nam = new QNetworkAccessManager(this);

    connect(nam, SIGNAL(finished(QNetworkReply*)),
             this, SLOT(httpFinished(QNetworkReply*)));

    QNetworkReply* reply = nam->get(QNetworkRequest(httpUrl));

  QEventLoop eventLoop;

    connect(nam, SIGNAL(finished(QNetworkReply *)), &eventLoop, SLOT(quit()));
    eventLoop.exec();

}