is it possible merge two json object

[itviewer]

some function like this
json1.join(json2) or
json1.merge(json2) or
json1 += json2

[nlohmann]

This is an interesting question. Currently, there is no insert(InputIt first, InputIt last) function such as std::map::insert.

[nlohmann]

(I should definitely have another look at all the overloads of insert of the STL containers. For instance, std::map::iterator insert( const_iterator hint, const value_type& value ); exists, but an insert function with the same signature is currently only allowed for arrays.)

[andnp]

I have also needed this type of functionality. For the time being until this is closed, I have been using this code which modifies the json object in place.

One thing to consider is the desired behavior when j1 and j2 have matching keys. In this case j1 is over-written by values in j2.

Hopefully this helps for now.

void extendJson(json &j1, const json &j2) {
    for (const auto &j : json::iterator_wrapper(j2)) {
        j1[j.key()] = j.value();
    }
}

[nlohmann]

Thanks for the hint. I shall have a look at the insert functions of the STL containers and propose an extension here.