I am trying to parse the json value for a field if it exists and set it to std::experimental::nullopt if it does not.
#include "json.hpp"
#include <experimental/optional>
namespace nlohmann {
template <typename T>
struct adl_serializer<std::experimental::optional<T>> {
static void to_json(json& j, const std::experimental::optional<T>& opt) {
if (opt == std::experimental::nullopt) {
j = nullptr;
} else {
j = *opt;
}
}
static void from_json(const json& j, std::experimental::optional<T>& opt) {
if (j.is_null()) {
opt = std::experimental::nullopt;
} else {
opt = j.get<T>();
}
}
};
}
namespace my_project {
struct Person {
std::string id;
std::string name;
std::experimental::optional<std::string> company;
};
void to_json(json& j, const Person& p) {
j = json {
{"id", p.id},
{"name", p.name},
{"company", p.company}
};
}
void from_json(const json& j, Person& p) {
p.id = j.at("id").get<std::string>();
p.name = j.at("name").get<std::string>();
// This works
try {
p.company = j.at("company").get<std::experimental::optional<std::string>>();
} catch(std::exception) {
p.company = std::experimental::nullopt;
}
// This does not work, but it would be nice to have it instead if using try/catch for multiple fields.
p.company = j.value("company", std::experimental::nullopt);
}
}
I am trying to parse the json value for a field if it exists and set it to std::experimental::nullopt if it does not.