error: qnetworkaccessmanager

Juandav93

trying to send a data by POST method to a php page receive these errors:

QEventLoop : Can not be used without QApplication QObject :: connect : Can not connect ( null) :: aboutToQuit () to QNativeWifiEngine :: CloseHandle ()

I work on windows, my code is:

Variable::Variable(QObject *parent) :
   QObject(parent)
{


}


void Variable::enviar()
{
man =  new QNetworkAccessManager(this);
   QNetworkRequest requerimiento(QUrl("http://127.0.0.1/ser/envio.php"));
   QByteArray postDatos;

   QUrlQuery consulta;
   consulta.addQueryItem("datos","hola");
   postDatos.append(consulta.toString());
   requerimiento.setHeader(QNetworkRequest::ContentTypeHeader,"application/x-www-form-urlencoded;charset=UTF-8");
   requerimiento.setHeader(QNetworkRequest::ContentLengthHeader,postDatos.length());

   resp = man->post(requerimiento,postDatos);

   connect(man, SIGNAL(finished(QNetworkReply*)), this, SLOT(replyFinished(QNetworkReply *)));

   }

Someone help me please

Paul Colby

Hi @Juandav93 :)

QEventLoop : Can not be used without QApplication

Have you initialised a QApplication object somewhere (usually in your main function)? What does that initialisation look like? Based on the error message, I suspect the problem is outside of the code you've pasted.

Tip: It's not likely to be the problem, but you should probably connect your signal handlers before issuing the network request. ie put connect before man->post.

Cheers.

Juandav93

hi, thanks for answering , look:

variable.h

#ifndef VARIABLE_H
#define VARIABLE_H

#include <QObject>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QNetworkReply>
#include <QUrlQuery>
#include <QDateTime>
#include <QFile>
#include <QDebug>
#include <QProcess>
#include <QEventLoop>

class Variable : public QObject
{
 Q_OBJECT
public:
    explicit Variable(QObject *parent = 0);
    void enviar();

public slots:
    void replyFinished (QNetworkReply *reply);


private:
   QNetworkAccessManager *man;
   QNetworkReply *resp;
   QProcess *proc;
};

#endif // VARIABLE_H

main:

#include "yei_threespace_api.h"
#include <stdio.h>
#include <signal.h>
#include "variable.h"

int main()
{
Variable d;
d.enviar();
return 0;
}

variable.cpp

#include "variable.h"
#include "yei_threespace_api.h"

Variable::Variable(QObject *parent) :
    QObject(parent)
{


}


void Variable::enviar()
{
    QNetworkRequest requerimiento(QUrl("http://127.0.0.1/ser/envio.php"));
    QByteArray postDatos;
    QUrlQuery consulta;
    consulta.addQueryItem("datos","hola");
    postDatos.append(consulta.toString());
    requerimiento.setHeader(QNetworkRequest::ContentTypeHeader,"application/x-www-form-urlencoded;charset=UTF-8");
    requerimiento.setHeader(QNetworkRequest::ContentLengthHeader,postDatos.length());

    man = new QNetworkAccessManager(this);
    connect(man, SIGNAL(finished()), this, SLOT(replyFinished(QNetworkReply *)));
    man->post(requerimiento,postDatos);



}

void Variable::replyFinished (QNetworkReply *reply)
{
    QString data = reply->readAll();


   // reply->deleteLater();
}

I did what you recommended me but still continous the error.

Paul Colby

@Juandav93 said:

I did what you recommended me

I can't see any QApplication being initialised in your main. It should look something like:

int main(int argc, char **argv)
{
    QApplication app(argc, argv);
    Variable d;
    d.enviar();
    return app.exec();
}

Given that you have no UI, you might want to use QCoreApplication instead, but if you're going to add a UI later, then stick with QApplication for now.

Cheers.

Juandav93

Hello, thank you very much for answering , the program sends the message to the PHP page but I now have a question, I have to do this every certain period of time, please me can help.

Joel Bodenmann

For any periodic task, use QTimer.

Juandav93

@Joel-Bodenmann said:

For any periodic task, use QTimer.

Thank you very much you both for your answers : D