NLOHMANN_JSON_SERIALIZE_ENUM potentially requires duplicate definitions

[jasonbeach]

As many others have said this is a pretty fantastic library.
I'm trying to serialize some enums and this works (with the right to_json and from_json functions defined but not shown here):

struct Foo_t
{
  enum class color
  { 
      none = -1,
      black = 0,
      red,
      blue,
      green
  };
  int number{0};
  color foo_color{color::none};
};

NLOHMANN_JSON_SERIALIZE_ENUM(Foo_t::color,
  {
    {Foo_t::color::none, nullptr},
    {Foo_t::color::black, "black"},
    {Foo_t::color::red, "red"},
    {Foo_t::color::blue, "blue"},
    {Foo_t::color::green, "green"}
  })

however if I want to use those string definitions independent of json then I have to define another mapping, something like

static const std::unordered_map<Foo_t::color, const std::string> color_map = 
{
    {Foo_t::color::none, ""},
    {Foo_t::color::black, "black"},
    {Foo_t::color::red, "red"},
    {Foo_t::color::blue, "blue"},
    {Foo_t::color::green, "green"}
};

and unfortunately this doesn't work:

NLOHMANN_JSON_SERIALIZE_ENUM(Foo_t::color, color_map)

because the macro is expecting something that can be converted to an array of std::pairs.

Is there way to not have to duplicate the definitions?

[jasonbeach]

I came up with a partial solution. In the macro, replace both lines:
static const std::pair<ENUM_TYPE, BasicJsonType> m[] = __VA_ARGS__;
with
static const std::vector<std::pair<ENUM_TYPE, std::string> > m = __VA_ARGS__;

as well as changing BasicJsonType to std::string in the lambda.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[paexter]

I would like to use NLOHMANN_JSON_SERIALIZE_ENUM in combination with magic_enum https://github.com/Neargye/magic_enum as follows:

NLOHMANN_JSON_SERIALIZE_ENUM( MyEnum, magic_enum::enum_entries<MyEnum> )

The required change would be minimal, but would be of great value for this kind of combination of libraries.