Storing a json parsed object using boost into a map c++

Question

Hello I'm using boost library c++ to parse a json object having this form :

{ "ser" : ["ser1","ser2"] , "ver" : ["ver1","ver2"] }

using pt::read_json(jsonobj, config) and now I'm looking to store the different parsed json object parts ( key and value ) into a map of strings and a vector of strings .

any idea please ?

Answer 1

Big Warning: Property Tree is NOT a JSON library. It has large limitations.

That said, if all you wish is a map of (vectors of) strings, then this might be adequate for your needs.

Let's make a shorthand for the map type:

using VMap = std::map<std::string, std::vector<std::string> >;

Now, let's make function to transform from a property tree into that VMap:

VMap to_map(ptree const& pt) {
    VMap m;
    for (auto& [k, v] : pt) {
        auto& m_entry = m[k];
        for (auto& [k, v] : boost::make_iterator_range(v.equal_range(""))) {
            m_entry.push_back(v.get_value<std::string>());
        }
    }
    return m;
}

Adding a print function we can demo it:

Live On Coliru

#include <boost/property_tree/ptree.hpp>
#include <boost/property_tree/json_parser.hpp>
#include <iostream>
#include <map>

using boost::property_tree::ptree;
using VMap = std::map<std::string, std::vector<std::string> >;

VMap to_map(ptree const&);
void print(VMap const&);

int main() {

    ptree config;
    {
        std::istringstream jsonobj(R"({ "ser" : ["ser1","ser2"] , "ver" : ["ver1","ver2"] })");
        read_json(jsonobj, config);
    }

    auto m = to_map(config);
    print(m);
}

VMap to_map(ptree const& pt) {
    VMap m;
    for (auto& [k, v] : pt) {
        auto& m_entry = m[k];
        for (auto& [k, v] : boost::make_iterator_range(v.equal_range(""))) {
            m_entry.push_back(v.get_value<std::string>());
        }
    }
    return m;
}

void print(VMap const& vm) {
    for (auto& [k, vv] : vm) {
        std::cout << k << ": {";
        for (auto& v: vv)
            std::cout << " " << v;
        std::cout << " }\n";
    }
}

Prints

ser: { ser1 ser2 }
ver: { ver1 ver2 }