Question about qobject and http

Jeronimo

Hi i am trying to download files of my webpage with http. But i want send the string since qobject connection or is not possible? The other thing i'm doing with functions but maybe will better or can be do with signal/slots like always.
Code:

Main.cpp:

#include <QCoreApplication>
#include <QDebug>
#include "downloader.h"
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    QObject::connect(&Downloader::instance(),&Downloader::testSignal,
                        [](){
         QString s="http://myweb/currxml.php";

       });
    return a.exec();
}

download.h:

#ifndef Downloader_H
#define Downloader_H

#include <QObject>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QUrl>
#include <QDateTime>
#include <QFile>
#include <QDebug>
class Downloader : public QObject
{
    Q_OBJECT
    Q_DISABLE_COPY(Downloader)
public:
    static Downloader &instance();
    explicit Downloader(QObject *parent = nullptr);
    QString s;
    //virtual ~Downloader(){}

    void doSomething();
signals:

    void testSignal();

public slots:
    //void testSlot();
    void replyFinished (QNetworkReply *reply);

private:
    QNetworkAccessManager *manager;

};

#endif // Downloader_H

downloader.cpp

#include "downloader.h"
#include <QDebug>


Downloader &Downloader::instance()
{
    static Downloader _instance;
    return _instance;
}

Downloader::Downloader(QObject *parent) : QObject(parent)
{
    doSomething();
}

void Downloader::doSomething()
{
   //emit testSignal();
    qDebug() << "It's working!!!!";
    manager = new QNetworkAccessManager(this);
    manager->get(QNetworkRequest(QUrl(s)));
    emit instance().testSignal();
}

void Downloader::replyFinished (QNetworkReply *reply)
{
    if(reply->error())
    {
        qDebug() << "ERROR!";
        qDebug() << reply->errorString();
    }
    else
    {
        //qDebug() << reply->header(QNetworkRequest::ContentTypeHeader).toString();
        //qDebug() << reply->header(QNetworkRequest::LastModifiedHeader).toDateTime().toString();
        //qDebug() << reply->header(QNetworkRequest::ContentLengthHeader).toULongLong();
        //qDebug() << reply->attribute(QNetworkRequest::HttpStatusCodeAttribute).toInt();
        //qDebug() << reply->attribute(QNetworkRequest::HttpReasonPhraseAttribute).toString();
        QString p = reply->request().url().fileName();
        QFile *file = new QFile("C:/Users/moh/"+p);
        if(file->open(QFile::Append))
        {
            file->write(reply->readAll());
            file->flush();
            file->close();
        }
        delete file;
    }

    reply->deleteLater();
}

SGaist

Hi,

First thing: do not create static QObject.

Make your _instance a pointer and initialize it the first time instance is called.

Also, isn't this question the same as the one you posted here ?

Jeronimo

@SGaist it's not similar because here i ask about how i can pass since my main function one string to my other class with qobject. in the other i ask about instances i think maybe i'm wrong. But the code is the same.

Jeronimo

@SGaist when you say make your instance like pointer can you say some example? Other question about this post, the code is the same but in the post i am asking about other thing . But anyways what you think i need to delete other post?

SGaist

Here you have an example.

If you think both subjects are unrelated, then keep both.

Jeronimo

@SGaist one question this can be a good way?
class:

//GlobalClass.h

class GlobalClass
{
public:
  static GlobalClass* get()
  {
    if ( m_instance == nullptr )
    {
      m_instance = new GlobalClass;
    }
    return m_instance;
  }
  void set_value( int value )
  {
    m_value = value;
  }

  int get_value()
  {
    return m_value;
  }

  ~GlobalClass()
  {
    delete m_instance;
  }

private:
  GlobalClass() : m_value( 0 )
  {
  }

  static GlobalClass* m_instance;

  int m_value;
};

And then i can use, using this:

GlobalClass::get()->set_value(2);
auto val = GlobalClass::get();

SGaist

Yes it's one correct way to implement a singleton.