How to convert XML to JSON in C++?

Question

I came across How to convert XML to JSON in ASP.NET C# (link) and one in javascript (at goessner.net/download/prj/jsonxml/). But have yet to find one in c++ that takes just a st

Answer 1

I implemented this function to convert xml to json using jsoncpp & rapidxml libraries, maybe will help someone. To compile : g++ -o xmltojson main.cpp -ljsoncpp. Tested on debian 9 only.

#include 
#include 
#include 
#include 

#include 
#include 

void parse_node_tree(const rapidxml::xml_node<>* node, Json::Value& parent)
{
    Json::Value obj(Json::objectValue);

    std::multiset array;
    for(rapidxml::xml_node<> *child = node->first_node(); child != nullptr; child = child->next_sibling())
    {
        if(child->type() != rapidxml::node_element)
                continue;

        array.insert(child->name());
    }

    if(node->value_size() > 0)
    {
        obj["#text"] = node->value();
    }

    bool hasChilds = false;

    for(rapidxml::xml_attribute<> *attr = node->first_attribute(); attr != nullptr; attr = attr->next_attribute())
    {
        hasChilds = true;
        obj[attr->name()] = attr->value();
    }

    for(rapidxml::xml_node<> *child = node->first_node(); child != nullptr; child = child->next_sibling())
    {
        if(child->type() != rapidxml::node_element)
                   continue;

        hasChilds = true;

        Json::Value& next = obj[child->name()];
        if(array.count(child->name()) > 1 && !next.isArray())
        {
                next = Json::arrayValue;
        }

        parse_node_tree(child, next);
    }

    // set result.
    if(parent.isArray())
    {
        parent.append(obj);
    }
    else
    {
        if(obj.isArray() || hasChilds)
            parent = obj;
        else
            parent = node->value();
    }
}


// convert xml string to json
std::string xmltojson(const std::string& xml)
{
    char xml_text[xml.size()+1];

    memset(xml_text, 0, xml.size());
    strncpy(xml_text, xml.c_str(), xml.size());
    xml_text[xml.size()] = '\0';

    rapidxml::xml_document<> doc;

    try
    {
            doc.parse<0>(xml_text);
    }
    catch(rapidxml::parse_error& exp)
    {
        std::cout << exp.what() << std::endl;
        return std::string();
    }

    rapidxml::xml_node<> *node = doc.first_node();
    if(node == nullptr)
        return std::string();

    Json::Value jdoc;
    Json::Value& jroot = jdoc[node->name()];

    parse_node_tree(node, jroot);

    Json::FastWriter fast_writer;
    return fast_writer.write(jdoc);
}

int main(int argc, char** argv)
{
    // xml
    std::string test_xml = "Mercato di testGiovedi 18 dicembre 2003 16.05.295Miami American CafeIT07654930130Viale Carlo Espinasse 5, Como13302Filiberto GilardiIT87654770157    Via Biancospini 20, Messina8 1302EidonIT887511231Via Bassini 17/2, Milano18 202SkillNetIT887642131Via Chiasserini 11A, Milano2412EidonIT04835710965Via Cignoli 17/2, Roma11125Miami American CafeIT07654930130Viale Carlo Espinasse 5, Como13302Filiberto GilardiIT87654770157Via Biancospini 20, Messina81302EidonIT887511231Via Bassini 17/2, Milano18202SkillNetIT887642131Via Chiasserini 11A, Milano24202SkillNetIT887642131Via Chiasserini 11A, Milano2412EidonIT04835710965Via Cignoli 17/2, Roma1112";

    // convert
    std::string json = xmltojson(test_xml);

    // log
    std::cout << test_xml << std::endl;
    std::cout << std::endl;
    std::cout << json << std::endl;

    return 0;
}