try_emplace.md

jsoncons::basic_json::try_emplace

template <typename T>
pair<object_iterator, bool> try_emplace(const string_view_type& key, 
                                        Args&&... args); (1)

template <typename T>
object_iterator try_emplace(const_object_iterator hint, 
                            const string_view_type& key, 
                            Args&&... args); (2)

Parameters

key

The key used both to look up and to insert if not found

hint

Iterator to the position before which the new element will be inserted

args        

Arguments to forward to the constructor of the element

Return value

(1) returns a pair consisting of first, an iterator to the inserted value or the already existing value, and second, a bool indicating whether the insertion took place (true for insertion, false for no insertion.)

(2) returns an iterator to the inserted value or the already existing value.

Exceptions

Throws std::domain_error if not a json object.

Example

json a;

a.try_emplace("object1",json());
a.try_emplace("field1","value1");
a["object1"].try_emplace("field2","value2");

std::cout << a << '\n';

Output:

{"field1":"value1","object1":{"field2":"value2"}}