How do you combine many QDomDocumentFragments into a QDomDocument?

[falconium]

I have the following code, but it doesn't seem to work. First of all, 'fragment' seems to be empty with debugger despite I call createDocumentFragment().
Below part for parsing XML document inside 'data' is to ensure that the source has data. All iterated item has.
Why fragment is empty? Thanks!

if (mergedXML.documentElement().isNull())
    {
        QDomElement root = mergedXML.createElement("MergedMeasurements");
        mergedXML.appendChild(root);
    }
 
    foreach (XMLStruct data, mainXMLList)
    {
        QDomDocumentFragment fragment = data.getXMLDocument()->createDocumentFragment();  // This creates the fragment from QDomDocument.
        mergedXML.firstChild().appendChild(fragment);
        for (int i=0; i<data.getXMLDocument()->childNodes().count(); i++)
        {
            if (data.getXMLDocument()->childNodes().at(i).nodeName()=="OMeS")
                for (int j=0; j<data.getXMLDocument()->childNodes().at(i).childNodes().count(); j++)
                {
                if (data.getXMLDocument()->childNodes().at(i).childNodes().at(j).nodeName()=="PMSetup")
                {
                    for (int k=0; k<data.getXMLDocument()->childNodes().at(i).childNodes().at(j).childNodes().count(); k++)
                    {
                        if (data.getXMLDocument()->childNodes().at(i).childNodes().at(j).childNodes().at(k).nodeName()=="extraInfoSetup")
                        {
                            QDomNode x = data.getXMLDocument()->childNodes().at(i).childNodes().at(j).childNodes().at(k);
                            log(x.firstChildElement("measurementName").text());
                        }
                    }
                }
            }
        }
 
    }

if (mergedXML.documentElement().isNull())
    {
        QDomElement root = mergedXML.createElement("MergedMeasurements");
        mergedXML.appendChild(root);
    }

    foreach (XMLStruct data, mainXMLList)
    {
        QDomDocumentFragment fragment = data.getXMLDocument()->createDocumentFragment();  // This creates the fragment from QDomDocument.
        mergedXML.firstChild().appendChild(fragment);
        for (int i=0; i<data.getXMLDocument()->childNodes().count(); i++)
        {
            if (data.getXMLDocument()->childNodes().at(i).nodeName()=="OMeS")
                for (int j=0; j<data.getXMLDocument()->childNodes().at(i).childNodes().count(); j++)
                {
                if (data.getXMLDocument()->childNodes().at(i).childNodes().at(j).nodeName()=="PMSetup")
                {
                    for (int k=0; k<data.getXMLDocument()->childNodes().at(i).childNodes().at(j).childNodes().count(); k++)
                    {
                        if (data.getXMLDocument()->childNodes().at(i).childNodes().at(j).childNodes().at(k).nodeName()=="extraInfoSetup")
                        {
                            QDomNode x = data.getXMLDocument()->childNodes().at(i).childNodes().at(j).childNodes().at(k);
                            log(x.firstChildElement("measurementName").text());
                        }
                    }
                }
            }
        }
        
    }

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[wysota]

What is this supposed to do? Because right now you are creating an empty document fragment and attaching this empty fragment somewhere.

[falconium]

Hi wysota,

'data' is a class (XMLStruct) storing XML document. This XML data is stored in form of a QDomDocument variable, and this data is gathered by calling method getXMLDocument() of class. I want to combine all these XML docs by iterating the QDomDocuments of XMLStruct list into one QDomDocument (called mergedXML).

Thanks!

[wysota]

So since you have the documents, what do you need the fragments for?

#include <QtXml>
 
int main(int argc, char **argv){
  QDomDocument doc1;
  doc1.setContent(QString("<doc1><tag1>text</tag1></doc1>"));
  QDomDocument doc2;
  doc2.setContent(QString("<doc2><tag2>text</tag2></doc2>"));
  QDomDocument merged;
  merged.setContent(QString("<merged><app1/><app2/></merged>"));
  QDomElement app1 = merged.documentElement().firstChildElement("app1");
  QDomElement app2 = merged.documentElement().firstChildElement("app2");
  app1.appendChild(doc1.documentElement());
  app2.appendChild(doc2.documentElement());
  qDebug() << merged.toString();
  return 0;
}

#include <QtXml>

int main(int argc, char **argv){
  QDomDocument doc1;
  doc1.setContent(QString("<doc1><tag1>text</tag1></doc1>"));
  QDomDocument doc2;
  doc2.setContent(QString("<doc2><tag2>text</tag2></doc2>"));
  QDomDocument merged;
  merged.setContent(QString("<merged><app1/><app2/></merged>"));
  QDomElement app1 = merged.documentElement().firstChildElement("app1");
  QDomElement app2 = merged.documentElement().firstChildElement("app2");
  app1.appendChild(doc1.documentElement());
  app2.appendChild(doc2.documentElement());
  qDebug() << merged.toString();
  return 0;
}

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Result:

<merged>
 <app1>
  <doc1>
   <tag1>text</tag1>
  </doc1>
 </app1>
 <app2>
  <doc2>
   <tag2>text</tag2>
  </doc2>
 </app2>
</merged>

<merged>
 <app1>
  <doc1>
   <tag1>text</tag1>
  </doc1>
 </app1>
 <app2>
  <doc2>
   <tag2>text</tag2>
  </doc2>
 </app2>
</merged>

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[falconium]

Thanks for this simple example! I have learnt a lot. So instead of creating a fragment of documents, one only need to append the document elements of the children documents. I suppose I can also append lower level elements, not just roots.