[Interest] Curious QNetworkAccessManager behavior.

[Tony Rietwyk]

Hi Jason,

You should only connect to QNetworkAccessManager::finished once - before 
sending any files.  You are adding another connection with each file.

 From https://doc.qt.io/qt-5/qobject.html:

By default, a signal is emitted for every connection you make; two 
signals are emitted for duplicate connections. You can break all of 
these connections with a single disconnect 
<https://doc.qt.io/qt-5/qobject.html#disconnect>() call. If you pass the 
Qt::UniqueConnection 
<https://doc.qt.io/qt-5/qt.html#ConnectionType-enum> /type/, the 
connection will only be made if it is not a duplicate. If there is 
already a duplicate (exact same signal to the exact same slot on the 
same objects), the connection will fail and connect will return an 
invalid QMetaObject::Connection 
<https://doc.qt.io/qt-5/qmetaobject-connection.html>.

Regards, Tony


On 1/11/2019 11:21 am, Jason H wrote:
> I'm uploading files with QNAM.
> QFile *file = new QFile(QString("%1/%2/%3").arg(_dataDir).arg(SERVER_SYNC_DIR).arg(filename));
> if (file->open(QIODevice::ReadOnly)) {
> QNetworkRequest req(QUrl(QString("%1/%2/%3").arg(_serverUrl.toString()).arg("post").arg(filename)));
> req.setHeader(QNetworkRequest::ContentTypeHeader, "application/octet-stream");
> QNetworkReply *reply = _nam.post(req, file);
> _uploads[reply] = file;
> connect(&_nam, &QNetworkAccessManager::finished, this, &ServerSyncFolder::handlePostFinished);
>
>
> void ServerSyncFolder::handlePostFinished(QNetworkReply *reply) {
> 	qDebug() << Q_FUNC_INFO << reply->url() << reply->errorString();
> 	if (_uploads.contains(reply)) {
> 		_uploads[reply]->close();
> 		_uploads[reply]->remove();
> 		_uploads[reply]->deleteLater();
> 		_uploads.remove(reply);
>
> 	}
> 	reply->deleteLater();
> }
> Every time I upload a file, the handlePostFinished gets calle once for each file I've uploaded. For example, upload files 1.jpg, 2.jpg, 3.jpg, 4.jpg:
>
> void ServerSyncFolder::handleDirectoryChanged(const QString &) "/var/mobile/Containers/Data/Application/8787E7C7-0940-4834-B6D5-1DF049AE4BEE/Documents/sync"
> // will now post my file, after post is complete I get:
> void ServerSyncFolder::handlePostFinished(QNetworkReply *) QUrl("http://10.12.0.37:57201/post/4.jpg") "Unknown error"
> void ServerSyncFolder::handlePostFinished(QNetworkReply *) QUrl("http://10.12.0.37:57201/post/4.jpg") "Unknown error"
> void ServerSyncFolder::handlePostFinished(QNetworkReply *) QUrl("http://10.12.0.37:57201/post/4.jpg") "Unknown error"
> void ServerSyncFolder::handlePostFinished(QNetworkReply *) QUrl("http://10.12.0.37:57201/post/4.jpg") "Unknown error"
>
> Server logs do not show that I am posting it repeatedly. It is calling my slot with the last URL it posted to, for as many files as I've uploaded so far.
>
> Anyone have an idea why?
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