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c++qtqt4foreachqt-maemo

How do I use foreach with QDomNodeList in Qt?


I'm new to Qt and I'm learning something new every day.
Currently, I'm developing a small application for my Nokia N900 in my free time.
Everything is fine, I am able to compile and run Maemo applications on the device.

I've just learned about the foreach keyword in Qt. (I know it is not in C++, so I didn't think about it until I accidentally stumbled upon a Qt doc that mentioned it.)
So, I decided to change my quite annoying and unreadable loops to foreach, but I failed with this:

QDomNodeList list = doc.lastChild().childNodes().at(1).firstChild().childNodes();
for (int x = 0; x < list.count(); x++)
{
    QDomElement node = list.at(x).toElement();
    // Do something with node
}

This is how I tried:

foreach (QDomElement node, doc.lastChild().childNodes().at(1).firstChild().childNodes())
{
    // Do something with node
}

For some reason the above code doesn't even compile. I get cryptic error messages from the compiler.

Could someone please explain to me how to get it right?

If the foreach loop doesn't support QDomNodeList, is there a way to handle XML files which supports foreach?

EDIT:

To clarify, // Do something with node is the following in this case:

EveCharacter chr;
chr.setName(node.attribute(EVE_NAME));
chr.setId(node.attribute(EVE_CHARACTER_ID).toInt());
acc->addCharacter(chr);

Where acc is of type EveAccount, which stores data in a QList<EveCharacter>.

The uppercase symbols are compile-time constant strings.
(I'm creating a client for the EVE Online API. This is from the method that receives the account characters XML and interprets it.)

This is how I create doc:

QDomDocument doc;
doc.setContent(reply->readAll());

Note that reply is a QNetworkReply* which is sent back from a QNetworkAccessManager.

However, as the EVE API works with XML, I do a lot of XML parsing very similar to this in many places in my application.
Most of the XMLs can be several hundred lines long and can contain quite non-regular data patterns, such as this one.


Solution

  • foreach only supports the container classes, so you cannot use it with a QDomNodeList.

    I'm not sure of you actual goal, but I find the QXmlSimpleReader and QXmlStreamReader to be the easiest way to deal with XML.

    Edit to match question edit:

    What you are trying to do looks like a prime candidate for XPath or XQuery. Take a look at the QtXmlPatterns module this will give you a set of character nodes without having to loop through all the other nodes.