Premature end of document with QXmlStreamReader

PaperMoon

Hello,

Need help please.

Using QXmlStreamReader, I am trying to parse XML received in QNetworkReply. A simple read to parse XML ends up with error 'Premature end of document'.

Thanks for any pointers/inputs.

Qt version 5.9.2
Linux Debian

The code that I have to receive and parse XML

Extract

        QNetworkReply* reply = manager.post(request, query.toUtf8());

        QEventLoop eventLoop;

        QObject::connect(reply, SIGNAL(finished()), &eventLoop, SLOT(quit()));
        eventLoop.exec();

        if (reply->error() != QNetworkReply::NoError)
        {
            qDebug() << "Network error: " << reply->error();
        }
        else
        {
            qDebug() << "Response XML " << reply->readAll();

            QByteArray res = reply->readAll();

            parseXML(res);
        }



void parseXML(QByteArray data)
{
    QXmlStreamReader xml(data);

    while (!xml.atEnd()) 
    {
        if (xml.readNext() != QXmlStreamReader::EndDocument) 
        {
            if (xml.isStartElement())
                qDebug() << qPrintable(xml.name().toString()) ;
        }
    }

    if (xml.hasError())
        qDebug() << "Error: Failed to parse xml " << qPrintable(xml.errorString());

}

XML received in QNetworkReply

"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n
<SOAP-ENV:Envelope xmlns:SOAP-ENV=\"http://schemas.xmlsoap.org/soap/envelope/\" xmlns:SOAP-ENC=\"http://schemas.xmlsoap.org/soap/encoding/\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:ns2=\"http://tempuri.org/ns2.xsd\" xmlns:ns1=\"http://tempuri.org/ns1.xsd\">
 <SOAP-ENV:Body>
  <ns1:getAirfieldList>
   <list>
    <item>
     <ICAO>YSSY</ICAO>
     <description>Sydney Intl</description>
     <runways>
      <item>
       <ends SOAP-ENC:arrayType=\"ns2:RunwayEnd[2]\">
        <item>
         <designator>16R</designator>
         <latitude>-33.929358000000001</latitude>
         <longitude>151.171603</longitude>
         <elevation>0</elevation>
        </item>
        <item>
         <designator>34L</designator>
         <latitude>-33.964275000000001</latitude>
         <longitude>151.18066099999999</longitude>
         <elevation>0</elevation>
        </item>
       </ends>
      </item>
      <item>
       <ends SOAP-ENC:arrayType=\"ns2:RunwayEnd[2]\">
        <item>
         <designator>07</designator>
         <latitude>-33.943750000000001</latitude>
         <longitude>151.163633</longitude>
         <elevation>0</elevation>
        </item>
        <item>
         <designator>25</designator>
         <latitude>-33.937539000000001</latitude>
         <longitude>151.189956</longitude>
         <elevation>0</elevation>
        </item>
       </ends>
      </item>
      <item>
       <ends SOAP-ENC:arrayType=\"ns2:RunwayEnd[2]\">
        <item>
         <designator>16L</designator>
         <latitude>-33.949618999999998</latitude>
         <longitude>151.18831700000001</longitude>
         <elevation>0</elevation>
        </item>
        <item>
         <designator>34R</designator>
         <latitude>-33.971097</latitude>
         <longitude>151.19391100000001</longitude>
         <elevation>0</elevation>
        </item>
       </ends>
      </item>
     </runways>
     <magneticVar>0</magneticVar>
    </item>
   </list>
  </ns1:getAirfieldList>
 </SOAP-ENV:Body>
</SOAP-ENV:Envelope>\r\n"

jsulm

@PaperMoon First: you need to wait for the reply - you cannot just read after you sent the request. Either use http://doc.qt.io/qt-5/qiodevice.html#waitForReadyRead or readyRead() signal.

Second: do not call readAll() twice!

qDebug() << "Response XML " << reply->readAll();
QByteArray res = reply->readAll(); // Here you will not get anything as you already read everything above!

PaperMoon

@jsulm Thank you so much! I modified the implementation based on your suggestion. And the error was resolved.

For anyone landing at this question in the forum, Qt examples directory has a lot of examples for similar cases. I found 'RSS Listing example' (Examples/Qt-5.9.2/xml/rsslisting) to be helpful for my scenario.