XML edit

[SombreroMickey]

Hi guys,
lḿ writing few rows of code to edit XML like this:

<?xml version="1.0" encoding="UTF-8"?>
<data>
  <fam_number>123</fam_number>
</data>

<?xml version="1.0" encoding="UTF-8"?>
<data>
  <fam_number>123</fam_number>
</data>

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So i google it, then l tought that, this should write xml (loaded by qresource):

QDomDocument doc;
    QDomElement xmlroot= doc.createElement ("data");
    doc.appendChild (xmlroot);
    QStandardItemModel *model = new QStandardItemModel(0,0);
    QStandardItem *root = model->item (0,0);
    QStandardItem *fam = root->child (0,0); // Here Segmantation FAULT
    fam->setText (family_number);
 
    QFile file(":/data.xml");
    if(!file.open (QIODevice::WriteOnly | QIODevice::Text)) // Here FAILED to open
        qDebug () << "Fail";
    QTextStream stream(&file);
    stream << doc.toString ();
    file.close ();

QDomDocument doc;
    QDomElement xmlroot= doc.createElement ("data");
    doc.appendChild (xmlroot);
    QStandardItemModel *model = new QStandardItemModel(0,0);
    QStandardItem *root = model->item (0,0);
    QStandardItem *fam = root->child (0,0); // Here Segmantation FAULT
    fam->setText (family_number);

    QFile file(":/data.xml");
    if(!file.open (QIODevice::WriteOnly | QIODevice::Text)) // Here FAILED to open
        qDebug () << "Fail";
    QTextStream stream(&file);
    stream << doc.toString ();
    file.close ();

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But l get SEG FAILED and FAILED to open.
Can you please help me ? Thanks