Json Serialization (Marshalling and unmarshalling)

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I need some example of how to serialize/deserilize from Json format to Object and from Object to Json. I used this example http://www.boost.org/doc/libs/1_47_0/libs/serialization/doc/index.html, but it only serialize to a simple text. In my project, for other requirenments, I am using boost library with success. I am almost sure that I do need some other specific library like Json-Spirit or standard QT library (QScriptEngine). Any simple example will be very appreciate.

This is an example of the Json files I must serialized to a class.

[{"DscTipoEstrutura":"Unidade de Neg\u00f3cio","FlgAtivo":true,"IdDominio":1,"IdTipoEstrutura":1,"NroOrdem":0},{"DscTipoEstrutura":"Regi\u00e3o","FlgAtivo":true,"IdDominio":1,"IdTipoEstrutura":2,"NroOrdem":1},{"DscTipoEstrutura":"Distrito","FlgAtivo":true,"IdDominio":1,"IdTipoEstrutura":3,"NroOrdem":2}]

Ps.: I found http://www.codeproject.com/KB/recipes/JSON_Spirit.aspx and http://boost-spirit.com/repository/applications/show_contents.php similiar to I need but, because I am C++ begnnier, I couldn't understand them neither run the example after some couple of hours. I need some simple example.

Posted 2-Sep-11 11:11am

Member 8202575

Updated 2-Sep-11 11:12am

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Philippe Mori 2-Sep-11 18:28pm

I don't think there would be easy solution in C++ as there is in language with dynamic object support like JavaScript or never release of C#.

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Gabriel_1986 · Answer 1 · 2011-10-30T08:42:00

Hi guys,
I have used a CodeProject tutorial to bring a solution so you should download the code associated to the tutorial first at this adress:
http://www.codeproject.com/KB/recipes/JSON_Spirit.aspx

Then you can adapt it to your project quite rapidly (thanks to the tutorial)
and you get this solution.

C++

#include "json_spirit.h"
#include <cassert>
#include <fstream>

#ifndef JSON_SPIRIT_VALUE_ENABLED
#error Please define JSON_SPIRIT_VALUE_ENABLED for the Value type to be enabled 
#endif

using namespace std;
using namespace json_spirit;

struct Address
{
    string DscTipoEstrutura_;
    bool FlgAtivo_;
    int IdDominio_;
    int IdTipoEstrutura_;
    int NroOrdem_;
};

bool operator==( const Address& a1, const Address& a2 )
{
    return ( a1.DscTipoEstrutura_ == a2.DscTipoEstrutura_ ) &&
           ( a1.FlgAtivo_         == a2.FlgAtivo_ ) &&
           ( a1.IdDominio_         == a2.IdDominio_ ) &&
           ( a1.IdTipoEstrutura_       == a2.IdTipoEstrutura_ ) &&
           ( a1.NroOrdem_      == a2.NroOrdem_ );
}

void write_address( Array& a, const Address& addr )
{
    Object addr_obj;

    addr_obj.push_back( Pair( "DscTipoEstrutura", addr.DscTipoEstrutura_ ) );
    addr_obj.push_back( Pair( "FlgAtivo",         addr.FlgAtivo_ ) );
    addr_obj.push_back( Pair( "IdDominio",         addr.IdDominio_ ) );
    addr_obj.push_back( Pair( "IdTipoEstrutura",       addr.IdTipoEstrutura_ ) );
    addr_obj.push_back( Pair( "NroOrdem",      addr.NroOrdem_ ) );

    a.push_back( addr_obj );
}

Address read_address( const Object& obj )
{
    Address addr;
	string strBool;

    for( Object::size_type i = 0; i != obj.size(); ++i )
    {
        const Pair& pair = obj[i];

        const string& name  = pair.name_;
        const Value&  value = pair.value_;

        if( name == "DscTipoEstrutura" )
        {
            addr.DscTipoEstrutura_ = value.get_str();
        }
        else if( name == "FlgAtivo" )
        {
			addr.FlgAtivo_ = value.get_bool();;//to be changed
        }
        else if( name == "IdDominio" )
        {
            addr.IdDominio_ = value.get_int();
        }
        else if( name == "IdTipoEstrutura" )
        {
            addr.IdTipoEstrutura_ = value.get_int();
        }
        else if( name == "NroOrdem" )
        {
            addr.NroOrdem_ = value.get_int();
        }
        else
        {
            assert( false );
        }
    }

    return addr;
}

void write_addrs( const char* file_name, const Address addrs[] )
{
    Array addr_array;

    for( int i = 0; i < 5; ++i )
    {
        write_address( addr_array, addrs[i] );
    }

    ofstream os( file_name );

    write_formatted( addr_array, os );

    os.close();
}

vector< Address > read_addrs( const char* file_name )
{
    ifstream is( file_name );

    Value value;

    read( is, value );

    const Array& addr_array = value.get_array();

    vector< Address > addrs;

    for( unsigned int i = 0; i < addr_array.size(); ++i )
    {
        addrs.push_back( read_address( addr_array[i].get_obj() ) );
    }

    return addrs;
}

int main()
{
    const Address addrs[5] = { { "Unidade de Neg\u00f3cio",		"true",	   1,	1,	0 },
                               { "Regi\u00e3o",     "true",    1,	2	,1 },
                               { "Distrito", "true",   1, 3,2   },
                               { "jkl", "false",   3,    3, 2 },
                               { "mno", "false", 2, 4, 2 } };

    const char* file_name( "demo.txt" );

    write_addrs( file_name, addrs );//de la représentation tabulée au JSON

    vector< Address > new_addrs = read_addrs( file_name );//du JSON à la représentation tabulée

    assert( new_addrs.size() == 5 );

    for( int i = 0; i < 5; ++i )
    {
        assert( new_addrs[i] == addrs[i] );
    }

	return 0;
}
</fstream></cassert>

Hope it helps and tell me if you have problems or if the solution is not what you expected.

By from France,
Gabriel