examples/nlohmann_define_type_non_intrusive_explicit.cpp

#include <iostream>
#include <nlohmann/json.hpp>

using json = nlohmann::json;
using namespace nlohmann::literals;

namespace ns
{
struct person
{
    std::string name;
    std::string address;
    int age;
};

void to_json(nlohmann::json& nlohmann_json_j, const person& nlohmann_json_t)
{
    nlohmann_json_j["name"] = nlohmann_json_t.name;
    nlohmann_json_j["address"] = nlohmann_json_t.address;
    nlohmann_json_j["age"] = nlohmann_json_t.age;
}

void from_json(const nlohmann::json& nlohmann_json_j, person& nlohmann_json_t)
{
    nlohmann_json_t.name = nlohmann_json_j.at("name");
    nlohmann_json_t.address = nlohmann_json_j.at("address");
    nlohmann_json_t.age = nlohmann_json_j.at("age");
}
} // namespace ns

int main()
{
    ns::person p = {"Ned Flanders", "744 Evergreen Terrace", 60};

    // serialization: person -> json
    json j = p;
    std::cout << "serialization: " << j << std::endl;

    // deserialization: json -> person
    json j2 = R"({"address": "742 Evergreen Terrace", "age": 40, "name": "Homer Simpson"})"_json;
    auto p2 = j2.template get<ns::person>();

    // incomplete deserialization:
    json j3 = R"({"address": "742 Evergreen Terrace", "name": "Maggie Simpson"})"_json;
    try
    {
        auto p3 = j3.template get<ns::person>();
    }
    catch (const json::exception& e)
    {
        std::cout << "deserialization failed: " << e.what() << std::endl;
    }
}