QXmlStreamReader ends up in an endless loop when tag names have ":" double points

[RoadCoder]

Hello,
i have a problem with QXmlStreamReader. I have existing xml files for configuration
and i try to parse these files. Does anyone know why? I can't find the reason. I have
prepared a minimal example with two xml files and a main.cpp. With ExampleB.xml
the code works fine, with ExampleA.xml the code ends in an endless loop in line 6 of
the xml file.

ExampleA.xml (with double points in tag names)

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
<config>
	<metadata>
		<name>Configuration name</name>
		<calibration>
			<system:setup>Setup></system:setup>
			<system:min>Min value></system:min>
			<system:max>Max value></system:max>
			<system:spi>SPI config></system:spi>
			<system:i2c>I2C config></system:i2c>
		</calibration>
	</metadata>
</config>

ExampleB.xml (without double points in tag names)

<?xml version='1.0' encoding='UTF-8' standalone='yes' ?>
<config>
	<metadata>
		<name>Configuration name</name>
		<calibration>
			<system_setup>Setup></system_setup>
			<system_min>Min value></system_min>
			<system_max>Max value></system_max>
			<system_spi>SPI config></system_spi>
			<system_i2c>I2C config></system_i2c>
		</calibration>
	</metadata>
</config>

main.cpp

#include <QCoreApplication>
#include <QFile>
#include <QXmlStreamReader>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    // QFile file("d:/Stefan/Documents/Qt/xmlbug/ExampleA.xml");
    QFile file("d:/Stefan/Documents/Qt/xmlbug/ExampleB.xml");

    QXmlStreamReader reader;

    // Open File
    if( file.open(QFile::ReadOnly | QFile::Text) )
    {
        // Parse through file
        reader.setDevice(&file);

        while ( (!reader.atEnd()) && (!reader.hasError()) )
        {
              if(reader.tokenType() == QXmlStreamReader::StartElement)
              {
                    if( reader.name().toString()=="calibration" )
                    {
                        QString tagName;
                        QString tagData;

                        while( !(reader.tokenType()==QXmlStreamReader::EndElement && reader.name().toString()=="calibration") )
                        {
                            if( reader.tokenType()==QXmlStreamReader::StartElement && reader.name().toString()!="calibration" )
                            {
                                tagName = reader.name().toString();
                                tagData = reader.readElementText();
                                qDebug() << "Setup" << tagName << tagData;
                            }

                            reader.readNext();
                            qDebug() << reader.name().toString() << reader.lineNumber();
                        }
                    }
              }

              qDebug() << reader.name().toString() << reader.lineNumber();
              reader.readNext();
        }

        qDebug() << "Close File";

        // Close File
        file.close();
    }

    return a.exec();
}

[JonB]

@RoadCoder
Putting a colon (:) in an XML tag name mean it is in a namespace. Your <system:setup> is an XML element named setup in a namespace called system.

system would normally be defined as namespace via an earlier e.g.:

<config xmlns:system="https://www.somewhere.com/something">

You don't have that, I don't know whether system might be a recognised namespace, though I don't think so.

A tag in a namespace may affect your parsing/searching, but it shouldn't make anything "hang"/"loop" endlessly. Unless your code does that, I haven't looked. If you are stuck in your while loop you can use the qDebug() output to show you what is going on.

You can't use : in tag names of your own, if that is what you're asking.