encode_json.md

jsoncons::encode_json

Encode a C++ data structure to a JSON formatted string or stream. encode_json will work for all types that have json_type_traits defined.

#include <jsoncons/encode_json.hpp>

template <class T, class CharContainer>
void encode_json(const T& val, CharContainer& cont, 
    const basic_json_encode_options<CharContainer::value_type>& options  
        = basic_json_encode_options<CharContainer::value_type>(),
    indenting indent = indenting::no_indent);                                   (1)

template <class T, class CharT>                                             
void encode_json(const T& val, std::basic_ostream<CharT>& os, 
    const basic_json_encode_options<CharT>& options  
        = basic_json_encode_options<CharT>(),
    indenting indent = indenting::no_indent);                                   (2) 

template <class T, class CharContainer>
void encode_json_pretty(const T& val, CharContainer& cont, 
    const basic_json_encode_options<CharContainer::value_type>& options  
        = basic_json_encode_options<CharContainer::value_type>());              (3) (since 0.155.0)

template <class T, class CharT>
void encode_json_pretty(const T& val, std::basic_ostream<CharT>& os, 
    const basic_json_encode_options<CharT>& options 
        = basic_json_encode_options<CharT>());                                  (4) (since 0.155.0)        

template <class T, class CharT>
void encode_json(const T& val, basic_json_visitor<CharT>& encoder);             (5)

template <class T, class CharContainer, class Allocator, class TempAllocator>
void encode_json(const allocator_set<Allocator,TempAllocator>& alloc_set,
    const T& val, CharContainer& cont, 
    const basic_json_encode_options<CharContainer::value_type>& options  
        = basic_json_encode_options<CharContainer::value_type>(),
    indenting indent = indenting::no_indent);                                   (6) (since 0.171.0)

template <class T, class CharT, class Allocator, class TempAllocator>                                             
void encode_json(const allocator_set<Allocator,TempAllocator>& alloc_set,
    const T& val, std::basic_ostream<CharT>& os, 
    const basic_json_encode_options<CharT>& options  
        = basic_json_encode_options<CharT>(),
    indenting indent = indenting::no_indent);                                   (7) (since 0.171.0)

(1) Encode val into a character container with the specified (or defaulted) options.

(2) Encode val to an output stream with the specified (or defaulted) options.

Functions (3)-(4) are identical to (1)-(2) except indenting is on.

(5) Transform val into json events and stream through an encoder.

Functions (6)-(7) are identical to (1)-(2) except an allocator_set is passed as an additional argument.

Parameters

val	C++ data structure
visitor	JSON output visitor
options	Serialization options
os	Output stream
indenting	indenting::indent to pretty print, indenting::no_indent for compact output

Return value

None

Examples

Map with string-tuple pairs

#include <iostream>
#include <map>
#include <tuple>
#include <jsoncons/json.hpp>

using namespace jsoncons;

int main()
{
    using employee_collection = std::map<std::string,std::tuple<std::string,std::string,double>>;

    employee_collection employees = 
    { 
        {"John Smith",{"Hourly","Software Engineer",10000}},
        {"Jane Doe",{"Commission","Sales",20000}}
    };

    std::cout << "(1)\n" << std::endl; 
    encode_json(employees,std::cout);
    std::cout << "\n\n";

    std::cout << "(2) Again, with pretty print\n" << std::endl; 

    encode_json(employees, std::cout, indenting::indent);
}

Output:

(1)

{"Jane Doe":["Commission","Sales",20000.0],"John Smith":["Hourly","Software Engineer",10000.0]}

(2) Again, with pretty print

{
    "Jane Doe": ["Commission","Sales",20000.0],
    "John Smith": ["Hourly","Software Engineer",10000.0]
}

Contain JSON output in an object (prettified output)

#include <iostream>
#include <map>
#include <tuple>
#include <jsoncons/json.hpp>

using namespace jsoncons;

int main()
{
    std::map<std::string, std::tuple<std::string, std::string, double>> employees =
    {
        {"John Smith",{"Hourly","Software Engineer",10000}},
        {"Jane Doe",{"Commission","Sales",20000}}
    };

    json_stream_encoder encoder(std::cout);

    encoder.begin_object();
    encoder.key("Employees");
    encode_json(employees, encoder);
    encoder.end_object();
    encoder.flush();
}

Output:

{
    "Employees": {
        "Jane Doe": ["Commission","Sales",20000.0],
        "John Smith": ["Hourly","Software Engineer",10000.0]
    }
}

Contain JSON output in an object (compressed output)

#include <iostream>
#include <map>
#include <tuple>
#include <jsoncons/json.hpp>

using namespace jsoncons;

int main()
{
    std::map<std::string, std::tuple<std::string, std::string, double>> employees =
    {
        {"John Smith",{"Hourly","Software Engineer",10000}},
        {"Jane Doe",{"Commission","Sales",20000}}
    };

    compact_json_stream_encoder encoder(std::cout);

    encoder.begin_object();
    encoder.key("Employees");
    encode_json(employees, encoder);
    encoder.end_object();
    encoder.flush();
}

Output:

{"Employees":{"Jane Doe":["Commission","Sales",20000.0],"John Smith":["Hourly","Software Engineer",10000.0]}}

See also

basic_json_visitor

basic_json_options

basic_json_encoder

decode_json