How can I "merge" the content of two QVariantMap in Qt5?

Question

I have two QVariantMap instances A and B.

In A I have the following strings: [ "key1" => "Cat", "key2" => "Dog", "key3" => "Mouse" ]. In B I have the following strings: [ "key1" => "Cat", "key4" => "Dog", "key3" => "Bison" ].

I want to merge them into a third QVariantMap instance C so that it contains the following:

[ "key1" => "Cat", "key2" => "Dog", "key3" => "Bison", "key4" => "Dog" ].

Note how there is only one "Cat" and how "Mouse" was replaced by "Bison".

Is there a way to do this in Qt5 without writing my own utility function to do it?

Answer 1

Since 5.15, Qt provides an insert overload taking another QMap as parameter, which inserts all key/value pairs from the other map into the original map, overwriting existing keys:

    QVariantMap A;
    QVariantMap B;

    A.insert("key1", "Cat");
    A.insert("key2", "Dog");
    A.insert("key3", "Mouse");

    B.insert("key1", "Cat");
    B.insert("key4", "Dog");
    B.insert("key3", "Bison");

    QVariantMap C(A);
    C.insert(B);

    // C now holds the combined keys&values of A & B;
    // for keys existing in both A and B, the values from B are taken!