How to use value for std::experimental::optional type?

[dianambb]

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);
    }
}

[theodelrieu]

I advise you to take a look at #278, don't hesitate to provide feedbacks about the proposed behaviours :)

[nlohmann]

@dianambb Did you have the chance to check the issue mentioned in #760 (comment)?

[nlohmann]

💤 I closed this issue due to inactivity. Please feel free to add a comment and I shall reopen it.