jsonVariant is a generic C++ header-only library for deserializing JSON strings to the recursive variants and serializing recursive variants to JSON strings

Installation

Copy the header file into your project or use cmake for installing header to your system folders

Prerequisities

No addtional dependencies except C++ standard libraries.

Build & Install

• cmake -DCMAKE_BUILD_TYPE=Release -DBUILD_EXAMPLES=ON . - Replace Release with Debug for a build with debug symbols.
• cmake . && make install - use sudo user for installing to system directories on Linux

Usage

Read json string to recursive variant structure. For advanced json schema validation and parsing with generic approach see examples

#include "jsonVariant.hpp"

namespace
{
    struct Team
    {
        struct Player
        {
            std::string name;
            double averageScoring;
        };
        
        int64_t id;
        std::string coach;
        std::string assistant;
        std::vector<Player> players;
    };
    
    std::string jsonString(R"(
    {
        "id": 2,
        "coach": "Samuel Motivator",
        "assistant": null,
        "players": [{
                "name": "Stephen",
                "averageScoring": 16.4
            },
            {
                "name": "Anthony",
                "averageScoring": 14.8
            }
        ]
    })");
}

int main()
{
    std::string errorStr;
    JsonSerialization::Variant variant;
    if (!JsonSerialization::Variant::fromJson(jsonString, variant, &errorStr))
    {
        printf("Unable to parse json with error: %s", errorStr.c_str());
        return -1;
    }
    
    Team team;
    const JsonSerialization::VariantMap & objectMap = variant.toMap();
    team.id = objectMap.at("id").toInt64();
    team.coach = objectMap.at("coach").toString();
    if (!objectMap.at("assistant").isNull())
        team.coach = objectMap.at("assistant").toString();
    
    const JsonSerialization::VariantVector & playersVector = objectMap.at("players").toVector();
    for (const JsonSerialization::Variant & v : playersVector)
    {
        Team::Player player;
        const JsonSerialization::VariantMap & playersMap = v.toMap();
        player.name = playersMap.at("name").toString();
        player.averageScoring = playersMap.at("averageScoring").toDouble();
        team.players.push_back(player);
    }
    
    return 0;
}

Create recursive structure and than flush it as json string

#include "jsonVariant.hpp"

namespace
{
    struct Team
    {
        struct Player
        {
            std::string name;
            double averageScoring;
        };
        
        int64_t id;
        std::string coach;
        std::string assistant;
        std::vector<Player> players;
    };
}

int main()
{
    Team team;
    team.id = 2;
    team.coach = "Samuel Motivator";
    team.players =
    {
        { "Stephen", 16.4 },
        { "Anthony", 14.8 }
    };
    
    JsonSerialization::VariantVector playersVector;
    for (const Team::Player & player : team.players)
    {
        playersVector.push_back(std::move(JsonSerialization::VariantMap
        {
            { "name", player.name },
            { "averageScoring", player.averageScoring }
        }));
    }
    
    JsonSerialization::VariantMap variantMap
    {
        { "id", team.id },
        { "coach", team.coach },
        { "assistant", nullptr },
        { "players", std::move(playersVector) }
    };
    
    JsonSerialization::Variant finalVariant(variantMap);
    printf("%s", finalVariant.toJson().c_str());
    return 1;
}