Parsing XML file with QXmlStreamReader

[Mery_lamb]

Hello;

Please find below the code (I found in a website) and I use it to parse the xml file

test1_number  = 0; 
if (reader.readNextStartElement()) {
        if (reader.name() == "root"){
            while(reader.readNextStartElement()){
                if(reader.name() == "FirstChild"){
                    while(reader.readNextStartElement()){
                        if(reader.name() == "test1"){
                            qDebug << "Hello Test1 \n"; 
                           test1_number ++ ; 
                        }
                        else
                            reader.skipCurrentElement();
                    }
                }
                else
                    reader.skipCurrentElement();
            }
        }
        else
            reader.raiseError(QObject::tr("Incorrect file"));
}

xml file :

<?xml version="1.0" encoding="UTF-8"?>
<!--example with no DTD-->
<root>
   <FirstChild>
		<test1 type= "girl"> 
			<name> asmaa </name>
			<age> 14</age>
		</test1>
                
		<test1 type= "boy"> 
			<name> boy </name>
			<age> 10</age>
		</test1>
   </FirstChild>
   <SecondChild>text3</SecondChild>
</root>            

I want to count number of test1 Item in the xml file but I always get 1 even if we have more than that in the file

Can anyone help me please

[SGaist]

This works as expected:

#include <QCoreApplication>
#include <QFile>
#include <QXmlStreamReader>
#include <QtDebug>

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);

    QFile file("test.xml");
    if(!file.open(QFile::ReadOnly | QFile::Text)){
        qDebug() << "Cannot read file" << file.errorString();
        exit(0);
    }

    QXmlStreamReader reader(&file);

    int test1_number  = 0;
    if (reader.readNextStartElement()) {
        if (reader.name() == "root" ){
            while(reader.readNextStartElement()) {
                qDebug() << "First level start element name" << reader.name();
                if(reader.name() == "FirstChild") {
                    while(reader.readNextStartElement()) {
                        qDebug() << "Second level start element name" << reader.name();
                        if(reader.name() == "test1"){
                            qDebug() << "Hello Test1 \n";
                            test1_number++ ;
                        }

                        reader.skipCurrentElement();
                    }
                } else {
                    reader.skipCurrentElement();
                }
            }
        } else {
            reader.raiseError(QObject::tr("Incorrect file"));
        }
    }

    qDebug() << "Number of 'test1'" << test1_number;

    return 0;
}

[SGaist]

Hi,

Are you following this one ?

[Mery_lamb]

@SGaist Yes I did I followed the second one

[SGaist]

I think you are missing a "reader.skipCurrentElement();" after your counter update.

You have more data under test1 and these you do not seem to want to parse. You current code will continue getting name and age and then stop since there are no more start element after it.

[Mery_lamb]

@SGaist but after the counter update I add a reader.skipCurrentElement(). please take a look to this part

if(reader.name() == "FirstChild"){
                    while(reader.readNextStartElement()){
                        if(reader.name() == "test1"){
                            qDebug << "Hello Test1 \n"; 
                           test1_number ++ ; 
                        }
                        else
                            reader.skipCurrentElement();
                    }
                }
                else
                    reader.skipCurrentElement();

[JonB]

@Mery_lamb
Debug out reader.name() at every stage to see where your reader is getting to.

[SGaist]

@Mery_lamb said in Parsing XML file with QXmlStreamReader:

@SGaist but after the counter update I add a reader.skipCurrentElement(). please take a look to this part

if(reader.name() == "FirstChild"){
                    while(reader.readNextStartElement()){
                        if(reader.name() == "test1"){
                            qDebug << "Hello Test1 \n"; 
                           test1_number ++ ; 
                        }
                        else
                            reader.skipCurrentElement();
                    }
                }
                else
                    reader.skipCurrentElement();

No you did not, it's in the else clause.

[Mery_lamb]

This post is deleted!

[Mery_lamb]

@JonB I did and I found that inside the if(reader.name() == "test1"), I get only one element which mean that maaaaybe I forget reader.skipCurrentElement() but I am not sure where to add it

[SGaist]

right after test1_number++.

Or just remove the else of that specific if since you are not doing any other processing of what is inside that element.

[Mery_lamb]

@SGaist
If I remove the else after the counter it will not show "test1 " at all. if I add the reader.skipCurrentElement() after the counter I get the same result

[JonB]

@Mery_lamb
I haven't looked at it/used this XML reader code. But I think you'll find that after you read the <test1 type= "girl"> you still have go down into the <name> asmaa </name>, <age> 14</age> stuff, and then you have to come out again to move onto the <test1 type= "boy"> .

Anyway, I wouldn't know without trying it myself.

[SGaist]

This works as expected:

#include <QCoreApplication>
#include <QFile>
#include <QXmlStreamReader>
#include <QtDebug>

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);

    QFile file("test.xml");
    if(!file.open(QFile::ReadOnly | QFile::Text)){
        qDebug() << "Cannot read file" << file.errorString();
        exit(0);
    }

    QXmlStreamReader reader(&file);

    int test1_number  = 0;
    if (reader.readNextStartElement()) {
        if (reader.name() == "root" ){
            while(reader.readNextStartElement()) {
                qDebug() << "First level start element name" << reader.name();
                if(reader.name() == "FirstChild") {
                    while(reader.readNextStartElement()) {
                        qDebug() << "Second level start element name" << reader.name();
                        if(reader.name() == "test1"){
                            qDebug() << "Hello Test1 \n";
                            test1_number++ ;
                        }

                        reader.skipCurrentElement();
                    }
                } else {
                    reader.skipCurrentElement();
                }
            }
        } else {
            reader.raiseError(QObject::tr("Incorrect file"));
        }
    }

    qDebug() << "Number of 'test1'" << test1_number;

    return 0;
}

[Mery_lamb]

@SGaist thank you for your help I was stuck in this error from last 3 days. it seems like I need to take another look to my Qt notes.