Please help me deserialize a derived class to base-class pointer. I attach the complete source code example.
request.hpp (no pair cpp file)
#ifndef REQUEST_HPP
#define REQUEST_HPP
#include <memory>
#include <string>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/archive/xml_iarchive.hpp>
namespace demo {
namespace common {
class request {
public:
static const int INVALID_ID = -42;
request()
: id_(INVALID_ID), timestamp_(0), source_ip_("unknown") {};
request(int id, long timestamp, const std::string& source_ip)
: id_(id), timestamp_(timestamp), source_ip_(source_ip) {};
virtual ~request() {};
int id() const { return id_; }
long timestamp() const { return timestamp_; }
std::string source_ip() const { return source_ip_; }
protected:
int id_;
long timestamp_;
std::string source_ip_;
private:
friend class boost::serialization::access;
template<class Archive>
void serialize(Archive& ar, const unsigned version) {
ar & BOOST_SERIALIZATION_NVP(id_);
ar & BOOST_SERIALIZATION_NVP(timestamp_);
ar & BOOST_SERIALIZATION_NVP(source_ip_);
}
};
typedef std::shared_ptr<request> request_ptr;
}
};
#endif
command.hpp (derived class)
#ifndef COMMAND_HPP
#define COMMAND_HPP
#include <memory>
#include <string>
#include <boost/serialization/export.hpp>
#include <demo/common/request.hpp>
namespace demo {
namespace common {
class command : public request {
public:
command(): name_("untitled") {};
explicit command(const std::string& name) : name_(name) {};
virtual ~command() {};
virtual void execute();
std::string name() const { return name_; }
protected:
std::string name_;
private:
friend class boost::serialization::access;
template<class Archive>
void serialize(Archive& ar, const unsigned version) {
ar & BOOST_SERIALIZATION_BASE_OBJECT_NVP(request);
ar & BOOST_SERIALIZATION_NVP(name_);
}
};
typedef std::shared_ptr<command> command_ptr;
}
};
BOOST_CLASS_EXPORT_KEY(demo::common::command)
#endif
command.cpp
#include "command.hpp"
#include <iostream>
BOOST_CLASS_EXPORT_IMPLEMENT(demo::common::command)
namespace demo {
namespace common {
void command::execute() {
std::cout << " I am '" + name_ +"' and I am executing..." << std::endl;
}
}
};
serializer.hpp
#ifndef SERIALIZER_HPP
#define SERIALIZER_HPP
#include <sstream>
#include <string>
/* classes to serialize */
#include <demo/common/request.hpp>
#include <demo/common/command.hpp>
namespace demo {
namespace common {
class serializer {
public:
serializer() : {};
template<typename T>
std::string serialize(const T& t){
std::stringstream stream;
boost::archive::xml_oarchive archive(stream);
archive << BOOST_SERIALIZATION_NVP(t);
std::string serialized = stream.str();
return serialized;
}
template<typename T>
void deserialize(const std::string& serialized, T& t) {
std::stringstream stream(serialized);
boost::archive::xml_iarchive archive(stream);
archive >> BOOST_SERIALIZATION_NVP(t);
}
};
}
}
#endif
sample usage
#include <iostream>
#include <demo/common/serializer.hpp>
#include <demo/common/command.hpp>
using namespace std;
using namespace demo::common;
int main(){
serializer serializer_;
command r("123"); // <-- (1) my desired way of declaring
//request* r = new command("123"); <-- (2) replacing with this makes all work!
//command* r = new command("123"); <-- (3) replacing with this crashes the app, like (1)
std::string s = serializer_.serialize(r);
std::cout << s << std::endl;
request* rr = nullptr;
serializer_.deserialize(s, rr); //this throws an exception
command* rrr = dynamic_cast<command*>(rr);
rrr->execute();
}
I thought I did everything that needs to be done, archives included before any class export, all default constructors initialize members..
Note that the serializable classes and the serializer are compiled to a lib file. Then that lib is used in two sub-projects that have access to the headers and have that lib linked. They use those classes to communicate with each other, they send serialized objects over network.
Why can't I deserialize a derived class to a base class pointer? I am using Boost 1.51 and VC11.
