在Boost序列化中，boost :: local_time :: local_date_time给出错误

Question

I'm trying to serialize MyData but boost::local_time::local_date_time gives error : "Error 1 error C2512: 'boost::local_time::local_date_time_base<>' : no appropriate default constructor available"

Below is the code :

// MyData.hpp file

struct MyData
{
std::string id;
std::string name;
boost::local_time::local_date_time time; 

private:
friend class boost::serialization::access;
template
void serialize(Archive &ar, const unsigned int version)
{
ar & id;
ar & name;
ar & time;  // when i comment this line, error goes off
} 

public:
MyData(void);
MyData(const parameter_strings & parms);

virtual ~MyData(void);
};
}

// MyData.cpp file

MyData::MyData(void)
{
}

MyData::~MyData(void)
{
}

MyData::MyData(const parameter_strings & parms)
{
// implementation aprt
}

BOOST_CLASS_EXPORT_IMPLEMENT(MyData); BOOST_CLASS_IMPLEMENTATION(MyData,boost::serialization::object_serializable); BOOST_CLASS_TRACKING(MyData,boost::serialization::track_selectively);

Please help on this topic, investing more time but till now no use.

Can i use posix date time to get current date and time ?? or where do i need to call the construtor for date-time.. ??

Thanks

Answer 1

The docs state :

The boost::date_time library is compatible with the boost::serialization library's text and xml archives. The list of classes that are serializable are:

• boost::gregoriandate
date_duration , date_period , partial_date , nth_day_of_week_in_month , first_day_of_week_in_month last_day_of_week_in_month , first_day_of_week_before , first_day_of_week_after greg_month , greg_day , greg_weekday
• boost::posix_time
ptime , time_duration , time_period

So, yes. But you should use ptime instead of local_date_time.

Now, first things first, the compiler is complaining that it doesn't know how to initialize the time member (since it has no default constructor). This has nothing to do with serialization:

struct Oops
{
    boost::local_time::local_date_time time; 
    Oops() { }
};

has the same problem already. Fix it:

struct FixedOops
{
    boost::local_time::local_date_time time; 
    FixedOops() : time(boost::local_time::not_a_date_time) 
    { 
    }
};

Now, to serializing:

#include <boost/archive/text_oarchive.hpp>
#include <boost/date_time/posix_time/time_serialize.hpp>
#include <boost/date_time/local_time/local_time.hpp>

struct parameter_strings {};

struct MyData
{
    std::string id;
    std::string name;
    boost::posix_time::ptime time; 

  private:
    friend class boost::serialization::access;
    template <typename Archive>
        void serialize(Archive &ar, const unsigned int version)
        {
            ar & id;
            ar & name;
            ar & time;  // when i comment this line, error goes off
        } 

  public:
    MyData() : time(boost::posix_time::not_a_date_time) { }
    MyData(parameter_strings const&) : time(boost::posix_time::not_a_date_time) { }
    virtual ~MyData() { };
};

int main()
{
    boost::archive::text_oarchive oa(std::cout);
    MyData data;

    oa << data;
}

So that was

• change to ptime
• include the serialization header for posix_time .

The program prints:

22 serialization::archive 10 0 0 0  0  0 0 0 0 15 not-a-date-time

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