Looping through QNetworkAccessManager get() routines, retrieve order on finish - c++

Question

I have a QNetworkAccessManager as a member of my class. I connect the finished signal from this manager to the replyFinished function I have written.
manager = new QNetworkAccessManager(this);
connect(manager, SIGNAL(finished(QNetworkReply*)),this,SLOT(replyFinished(QNetworkReply*)));
In a separate routine, I loop through a get call from the manager
for (int si = 0; si<numLines; si++)
{
QString line = lines[si];
manager->get(QNetworkRequest(QUrl(line)));
}
In my replyFinished slot routine, I know I may not receive the signals in the order they were performed in the loop, but is there any way I can obtain that information? That is, is there a clever way I can obtain "si" in my replyFinished routine? Thanks for the help!

Answer 1

QNetworkAccessManager::get() returns a pointer to the QNetworkReply object. This pointer is the same one that is passed your replyFinished() slot. You can use a QMap to store pairings of QNetworkReply* pointers and integers (si in your code).
Here is a working example;
#include <QCoreApplication>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QNetworkRequest>
#include <QUrl>
#include <QMap>
#include <QtDebug>
QNetworkAccessManager am;
void finished(QNetworkReply* reply);
QMap<QNetworkReply*, int> requests;
int main(int argc, char *argv[])
{
QCoreApplication a(argc, argv);
QObject::connect(&am, &QNetworkAccessManager::finished, finished);
QStringList links;
links << "http://google.com";
links << "http://taobao.com";
links << "http://stackoverflow.com";
links << "http://stackexchange.com";
links << "http://bing.com";
for (int i=0; i < links.size(); i++)
{
requests.insert(am.get(QNetworkRequest(QUrl(links[i]))), i);
}
return a.exec();
}
void finished(QNetworkReply* reply)
{
qDebug() << requests[reply];
}

Answer 2

The slot replyFinished(QNetworkReply*) receives pointer to the related reply object. This reply object contains all information about that reply (error code, headers, downloaded data, the URL of the content) and also it contains initial request (QNetworkReply::request()). So, it is possible to check the URL of the request or the URL of actual downloaded content. Note that those URLs may be different.
QNetworkReply::url():
Returns the URL of the content downloaded or uploaded. Note that the
URL may be different from that of the original request.
QNetworkReply::request():
Returns the request that was posted for this reply. In special, note
that the URL for the request may be different than that of the reply.
void MainWindow::replyFinished(QNetworkReply* reply)
{
qDebug() << reply->url();
qDebug() << reply->request().url();
}