Best Way to Read XML Tags w/o Specifying Tag's Name

masshakar

I just started Qt development yesterday. I'm trying to find a way to read an XML file, without specifying the tags' names (we have a variety of tags, and we cannot enumerate them all; some may/may not be children of a specific tag). I looked into qxmlstreamreader, but that still requires you to specify the tags' names.

How should I proceed? And thanks in advance.

SGaist

Hi and welcome to devnet,

What exactly do you want to do with the content of that file ?

panosk

Hi,
Creating a very "abstract" xml parser is not easy and it's quite error-prone. You have to know some (or at least one) parent or common tag names in order to have a starting point for any deeper "abstract" parsing. Basically, you have to move the parser step by step checking everything in the way. For example, you could use a simple function as an entry point for the following function when you meet a specific tag:

void XmlReader::readFragment()
{
    Q_ASSERT(m_reader->isStartElement()); //Make sure the xmlreader is at an opening tag
    const QString p = m_reader->qualifiedName().toString(); // From now on, you will work with this opening tag
    
	//Do what you want, for example handle attributes and their values
	for (auto i = 0; i < m_reader->attributes().count(); ++i) {
        ...
    }
    m_reader->readNext(); //Move on
	...
	
	//Do everything manually like this
	if (m_reader->isCharacters) {
		...
	} else if (m_reader->isEndElement()) {
		...
	}
	
	//or like this
        //Eventually, you have to check for the closing current tag, exit the function,
        //and return the control to the "entry point" function
	while (!m_reader->isEndElement() && !m_reader->qualifiedName().toString() == p) { 
		... //Do your work
                m_reader->readNext();
	}
	
}

However, with this approach, things can get extremely complicated if there are nested tags, for example:

<p>
   <note>
        <p>...</p>
   </note>
</p>

Maybe it would be easier to subclass QXmlStreamReader but it would help to provide some sample xml data and more info on what exactly you want to do.