[Qt-interest] QThread and QNetwork

[Jason H]

I haven't tried this, but you have to re-request it, and just wait. On a HTTP 
1.1 connection, only one side can talk at a time. So you have to issue your poll 
request and wait however long, to fill it.

You don't need threads to make this work, since the socket stuff is non-blocking 
already.


So I'd start bu putting 
db->startRequest(..)
in a while loop




----- Original Message ----
From: Matias Hernandez Arellano <msdark at archlinux.cl>
To: qt-interest at qt.nokia.com
Sent: Thu, May 26, 2011 12:56:15 PM
Subject: [Qt-interest] QThread and  QNetwork

(sorry for my english)

Hi, i'm trying do make an application to query a couchdb database using HTTP 
request to the _change API of the database.

To do this i create a class (DBCheck) that make a request to the _change API 
using the continuos feed, this is a HTTP connection that live forever and make 
possible to notify the client when a change occur in DB (real time, like Push 
notification).

Then i create another class (just for test) no show a notification (in console) 
of the change.

I connect this two classes using Signals and Slots.

Now i need to make this work with a GUI, the idea is show in a part of the GUI a 
"table" that auto--update any change in DB (when DB notify for changes)..

To do this i thought i need to use Threads, so for testing purpose i create a 
console application and try to run this, but i can't make that the Http class 
(DBCheck) run inside a thread an notify every change to the main thread (or 
other object using signals) .. i get an error about the diferents parents of the 
object..

So this is the code (without thread)
#ifndef DBCHECK_H
#define DBCHECK_H
#include <QNetworkAccessManager>
#include <QUrl>
#include <QObject>
#include <QByteArray>
#include <qjson/parser.h>
#include <QVariantMap>
#include <QDebug>
class QNetworkReply;
class DBCheck: public QObject
{
    Q_OBJECT
public:
    DBCheck();
    void startRequest(QUrl);
signals:
    void change();
private slots:
    void httpFinished();
    void httpReadyRead();
private:
    QUrl url;
    QNetworkAccessManager qnam;
    QNetworkReply *reply;
};

DBCheck::DBCheck()
{
}
void DBCheck::startRequest(QUrl url){
    reply = qnam.get(QNetworkRequest(url));
    connect(reply, SIGNAL(finished()),this, SLOT(httpFinished()));
    connect(reply, SIGNAL(readyRead()),this, SLOT(httpReadyRead()));
    return;
}
void DBCheck::httpFinished(){
    qDebug()<<"Finished";
    return;
}
void DBCheck::httpReadyRead(){
    this->result = this->reply->readAll();
    emit change();
}


//the other class
#ifndef NOTIF_H
#define NOTIF_H
#include <QObject>
#include <QDebug>
class Notif:public QObject{
    Q_OBJECT
public:
    Notif(){
    }
    ~Notif(){
    }
public slots:
    void notificar(){
        qDebug()<<"Cambio!";
    }
};
#endif // NOTIF_H

and the main.cpp
#include <QCoreApplication>
#include "dbcheck.h"
#include "notif.h"
#include <QDebug>
int main(int argc, char *argv[]){
     QCoreApplication app(argc, argv);
     DBCheck *db = new DBCheck();
     Notif *t = new Notif();
     QObject::connect(db,SIGNAL(change()),t,SLOT(notificar()));
     
db->startRequest(QUrl("http://127.0.0.1:5984/test/_changes?feed=continuous&since=39"));

     return app.exec();
}

How can i run the DBCheck object in a thread???

any guideline or idea would very appreciate ...

Thanks in advance.

Matías Hernandez Arellano
Ingeniero de Software/Proyectos en VisionLabs S.A
CDA Archlinux-CL
www.msdark.archlinux.cl




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