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I read the document of signal finished() , it does not say the finished() is always emitted. And I read the error() signal:

void QNetworkReply::error(QNetworkReply::NetworkError code) This signal is emitted when the reply detects an error in processing. The finished() signal will probably follow, indicating that the connection is over.

The code parameter contains the code of the error that was detected. Call errorString() to obtain a textual representation of the error condition.

Note: Do not delete the object in the slot connected to this signal. Use deleteLater().

See also error() and errorString().

Does the line The finished() signal will probably follow mean that, under some conditions, the QNetworkReply does not emit finished() ?

IAmInPLS
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zzy
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1 Answers1

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For QNetworkReply error signal we can certainly expect error codes that don't mean broken connection. For instance:

QNetworkReply::ContentNotFoundError 203 the remote content was not found at the server (similar to HTTP error 404)

The connection is definitely not finished yet in the case above. No finish signal emitted.

QNetworkReply::RemoteHostClosedError 2 the remote server closed the connection prematurely, before the entire reply was received and processed

The connection is definitely finished then. And finish signal was emitted.

Alexander V
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  • Could you give some example that connection is finished at error() ? – zzy Jul 17 '15 at 01:52
  • ConnectionRefusedError, RemoteHostClosedError and few more. – Alexander V Jul 17 '15 at 01:53
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    I have read the source code of QNetworkReply, all error signals are followed by a finished signal as far as I can find. Could you give some demo to show the case the error signal is emitted and finished signal is not emitted? – zzy Jul 17 '15 at 02:27
  • The demo would involve the server. I use finished signal like connect(&m_networkAccessManager, SIGNAL(finished(QNetworkReply*)), this, SLOT(handleFinished(QNetworkReply*))); to analyze an exact cause of failure. – Alexander V Jul 17 '15 at 04:57
  • So if the reply do not emit signal finished() according to your answer , how could you analyze its cause of failure? – zzy Jul 17 '15 at 06:10
  • No signal - no *fatal* failure. We have the app with many users. – Alexander V Jul 17 '15 at 07:01
  • My question is about whether the finished signal will be always emitted by QNetworkAccessManager after I sent the request. Your first answer have some mistakes, now it is clear. Thanks! – zzy Jul 17 '15 at 07:04
  • Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/83506/discussion-between-alexandervx-and-zzy). – Alexander V Jul 17 '15 at 07:05