jsonutil: Utilities to write serialization functions for nlohmann::json

Helper macros to write to_json(), from_json() for nlohmann::json, similar to MSGPACK_DEFINE in msgpack-c.

Quick Start

First of all, copy jsonutil.hh somewhere the compiler finds. jsonutil.hh needs to be included after nlohmann/json.hpp is included.

List member variables with JSON_MEMBER() macro.

#include <nlohmann/json.hpp>
#include "jsonutil.hh"
struct data{
   int x,y,z;
   JSON_MEMBER(x,y,z);
}

Then the struct data is ready to convert to nlohmann::json.

 data d={1,2,3};
 nlohmann::json j=d;
 std::cout<<j.dump(4)<<std::endl;

Map or Array

Structs marked with JSON_MEMBER() is serialized to json object by default. They can be serialized to json array to a dedicated json type yos::array_json.

 data d={1,2,3};
 yos::array_json j=d;
 std::cout<<j.dump(4)<<std::endl;

Or, a struct can be marked with JSON_MEMBER_ARRAY() to forbid serialization to json object.

#include <nlohmann/json.hpp>
#include "jsonutil.hh"
struct data_arr{
    int x,y,z;
    JSON_MEMBER_ARRAY(x,y,z);
}
int main(){
  data_arr d={1,2,3};
  nlohmann::json j=d;
}

Tested compilers

• gcc 5.4
• clang 3.8