nlohmann_json_reflect

a reflect extension for https://github.com/nlohmann/json, written by c++17
It can support any complex data structure which is defined by user.

Introduce

It is an extension for nlohmann/json.

Why write this? Because nlohmann/json reflect is not very powerful. It can not support complex Nested data structure.

For example: you can not use nlohmann/json reflect macro on the reflect structure nested by std container. Or you must implement the interface defined by nlohmann/json.

Anyway, it is not convenient for reflecting json to data structure directly, also data structure to json.

Use this extension, you can nest very complex data structure. Std container nest Std container, then nest reflect struct , then nest std container, and so on, layer after layer.

Note

Structure fields do not need to be forced a one-to-one correspondence with JSON field.
If the field is not existed in json but in structure , a default empty value is provided when reflect json to structure.

Usage

#include "json_reflect.hpp"

auto json_str = R"(
{
  "pi": 3.141,
  "happy": true,
  "name": "Niels",
  "nothing": "null",
  "answer": {
    "everything": 42
  },
  "list": [7, 8, 9, 9 ],
  "object": {
    "currency": "USD",
    "value": 42.99
  },
  "map":{
    "key1": [{"currency": "USD","value" : 40.99},{"currency": "USD","value" : 41.99},{"currency": "USD","value" : 42.99}],
    "key2": [{"currency": "USD","value" : 43.99},{"currency": "USD","value" : 44.99},{"currency": "USD","value" : 45.99}]
  },
  "taowa":{
	"keyzz": {
		"wa":{
			"zz":"zz"
		}
	}
  }
})";

struct obj {
	std::string currency;
	float value;
	REFLECT(obj, currency, value);
};

struct zzz {
	std::string zz;
	REFLECT(zzz, zz);
};

struct json_struct {
	std::string nothing;
	std::string name;
	bool happy;
	float pi;
	std::unordered_map <std::string, int> answer;
	std::vector<int> list;
	obj object;
	std::map<std::string, std::forward_list<obj>> map;
	std::unordered_map<std::string, std::map<std::string, zzz>> taowa;
	REFLECT(json_struct, nothing, name, happy, pi, answer, list, object, map, taowa);
};

int main() {	
	auto j_data = jreflect::from_json<json_struct>(json_str);
	auto j_str = jreflect::to_json(j_data);
	return 0;
}