Best way to write a custom class to a file using qt

Question

Hey all (out there :).
Which way is the best for writing a custom class to a file in Qt?
Thank you in advance.
Matthias

possible duplicate of [Serialization with Qt](http://stackoverflow.com/questions/2570679/serialization-with-qt).Look at this post, it may contain additional information. — UmNyobe, Jan 17 '13 at 10:06

score 5 · Accepted Answer · edited May 23 '17 at 10:32

EDIT: Question has been already asked. Serialization with Qt

The best way is to serialize using QDataStream. For a given class MyClass, you need to define new stream operators

QDataStream &operator<<(QDataStream &, const MyClass &);
QDataStream &operator>>(QDataStream &, MyClass &);

QDataStream is already capable of writing several Qt classes, mostly collections and other convenients classes like QImage, etc.... Note that you cannot serialize any subclass of QObject. There are reasons :), but limit yourself to the explanation that QObject itself doesn't provide neither copy constructors nor in\out stream functions like the one above.

Note that if your custom class derive a class already providing serialization, you need to call the stream operators for this superclass (the same principle as calling the constructor of the superclass when constructing the subclass).

it makes sense, that it isn't possible to serialize QOBject subclasses... :) that would cause a great huddle :D — Matthias -_-, Jan 17 '13 at 10:14

Best way to write a custom class to a file using qt

1 Answers1