How to merge two QJsonObjects in Qt?

I have:

QJsonObject obj1({"bla" : "lab"})
QJsonObject obj2({"bla2" : "lab2"})

and I need:

QJsonObject obj3({"bla" : "lab", "bla2" : "lab2"})

Or in JSON:

{
    "bla" : "lab"
}

{
    "bla2" : "lab2"
}

And I need:

{
    "bla" : "lab",
    "bla2" : "lab2"
}

How to achieve that?

Solution

I prefer to avoid explicit loops, so my solution would be to use a convertion to and from QVariantMap, aka QMap<QString, QVariant>:

1. Use QJsonObject::toVariantMap to convert all JSON objects to QVariantMap

2. Use QMap::insert to insert all maps into one

3. Use QJsonObject::fromVariantMap to convert the resulting map back to JSON object

Note: The proposed solution would work best if all JSON objects contain unique keys, because the documentation states:

If map contains multiple entries with the same key then the final value of the key is undefined.

Example

Here is a simple example I have prepared for you to demonstrate how the proposed solution could be implemented:

QJsonObject json1{{"foo_key", "foo_value"}};
QJsonObject json2{{"moo_key", "moo_value"}, {"boo_key", "boo_value"}};
QVariantMap map = json1.toVariantMap();

map.insert(json2.toVariantMap());

qDebug() << QJsonObject::fromVariantMap(map);

Result

This example produces the following result:

QJsonObject({"boo_key":"boo_value","foo_key":"foo_value","moo_key":"moo_value"})