Json Parser in C++ with Libcurl and Jsoncpp

Parser.h

#ifndef PARSER_H
#define PARSER_H

#include <iostream>
#include <string>

#include <curl/curl.h>
#include <jsoncpp/json/json.h>
#include <jsoncpp/json/reader.h>
#include <jsoncpp/json/writer.h>
#include <jsoncpp/json/value.h>

class Parser{
public:
    Parser(const std::string &s): url(s){}
    Parser(){}
    void request();
    std::string get_json_string();
    Json::Value get_json(){ return root; }
private:
    std::string url;
    Json::Value root;

    static std::size_t write_callback(char* in, std::size_t size, std::size_t nmemb, std::string* out);
};

std::string Parser::get_json_string(){
    Json::FastWriter fastWriter;
    return fastWriter.write(root);
}

std::size_t Parser::write_callback(char *in, size_t size, size_t nmemb, std::string *out){ 
    std::size_t total_size = size * nmemb;
    if(total_size){
        out->append(in, total_size);
        return total_size;
    }
    return 0;
}

void Parser::request(){
    // Parse raw Json string
    std::string str_buffer;
    CURL *curl = curl_easy_init();
    if(curl){
        CURLcode res;
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &str_buffer);
        res = curl_easy_perform(curl);
        if(res != CURLE_OK){
            std::cerr << "curl_easy_perform() failed:" << curl_easy_strerror(res) << std::endl;
            return;
        }
        curl_easy_cleanup(curl);
    }else{
        std::cout << "Could not initialize curl" << std::endl;
    }
    
    // Convert string to Json::Value
    Json::Reader reader;
    bool parse_status = reader.parse(str_buffer.c_str(), root);
    if (!parse_status){
        std::cerr  << "parse() failed: " << reader.getFormattedErrorMessages() << std::endl;
        return;
    }
}

#endif