Save and load QWebEngineHistory to a QWebEnginePage - qt

Question

I need to save the history of a QWebEnginePage and load it back. Therefore I want to store the history from page A in some structure and set it to page B.
In the documentation I found the following methods:
// Saves the web engine history history into stream.
QDataStream &operator<<(QDataStream &stream, const QWebEngineHistory &history)
// Loads the web engine history from stream into history.
QDataStream &operator>>(QDataStream &stream, QWebEngineHistory &history)
But honestly I don't know how to work with them.
I tried the following:
QWebEnginePage *m_history;
...
...
void setHistory(QWebEngineHistory *history){
QDataStream data;
data << history; //Hoping that the content of data is persistent after deleting of the QWebEnginePage where the history is coming from
data >> m_history;
}
And later on I want to load it back to the page:
m_history >> m_webEnginePage.history(); // Pseudo-Code
I know that the QWebEngineHistory of a QWebEnginePage is const, but then I'm wondering why are there even those two methods from above? Why is there a function that "loads the web engine history into history"?
The only alternative I can think of is storing my history in a QList, but managing this is not nice and could lead to more problems (because of the whole forward/backward button etc).
Thank you very much for your help.

Answer 1

No object can be saved, what is saved is the information associated with the object so you should not create QWebEngineHistory but save and/or load the information.
In the following example, the information is saved in a file when the application is closed and the startup is loaded.
#include <QtWebEngineWidgets>
int main(int argc, char *argv[]) {
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QApplication app(argc,argv);
const QString filename = "history.bin";
QWebEngineView view;
view.load(QUrl("https://stackoverflow.com"));
{// load
QFile file(filename);
if(file.open(QFile::ReadOnly)){
qDebug() << "load";
QDataStream ds(&file);
ds >> *(view.page()->history());
}
}
view.resize(640, 480);
view.show();
int ret = app.exec();
{// save
QFile file(filename);
if(file.open(QFile::WriteOnly)){
qDebug() << "save";
QDataStream ds(&file);
ds << *(view.page()->history());
}
}
return ret;
}
In the same way you can save it through QSettings:
#include <QtWebEngineWidgets>
int main(int argc, char *argv[]) {
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QApplication app(argc,argv);
QWebEngineView view;
view.load(QUrl("https://stackoverflow.com"));
{// load
QSettings settings;
QByteArray ba = settings.value("page/history").toByteArray();
QDataStream ds(&ba, QIODevice::ReadOnly);
ds >> *(view.page()->history());
}
view.resize(640, 480);
view.show();
int ret = app.exec();
{// save
QSettings settings;
QByteArray ba;
QDataStream ds(&ba, QIODevice::WriteOnly);
ds << *(view.page()->history());
settings.setValue("page/history", ba);
}
return ret;
}