bson.md

bson extension

The bson extension implements decode from and encode to the Binary JSON data format. You can either parse into or serialize from a variant-like data structure, basic_json, or your own data structures, using json_type_traits.

decode_bson

basic_bson_cursor

encode_bson

basic_bson_encoder

bson_options

Mappings between BSON and jsoncons data items

BSON data item	jsoncons data item	jsoncons tag
null	null
true or false	bool
int32 or int64	int64
datetime	int64
int32 or int64	uint64
datetime	uint64	epoch_milli
double	double
string	string
binary	byte_string	ext
0x04 (array )	array
0x03 (embedded document)	object

Examples

Document with string and binary

#include <jsoncons/json.hpp>
#include <jsoncons_ext/bson/bson.hpp>
#include <cassert>

int main()
{
    // Create some bson
    std::vector<uint8_t> buffer;
    bson::bson_bytes_encoder encoder(buffer);
    encoder.begin_object(); // The total number of bytes comprising 
                            // the bson document will be calculated
    encoder.key("Hello");
    encoder.string_value("World");
    encoder.key("Data");
    std::vector<uint8_t> bstr = {'f','o','o','b','a','r'};
    encoder.byte_string_value(bstr); // default subtype is user defined
    // or encoder.byte_string_value(bstr, 0x80); 
    encoder.end_object();
    encoder.flush();

    std::cout << "(1)\n" << byte_string_view(buffer) << "\n\n";

    /*
        0x27,0x00,0x00,0x00, // Total number of bytes comprising the document (40 bytes) 
            0x02, // URF-8 string
                0x48,0x65,0x6c,0x6c,0x6f, // Hello
                0x00, // trailing byte 
            0x06,0x00,0x00,0x00, // Number bytes in string (including trailing byte)
                0x57,0x6f,0x72,0x6c,0x64, // World
                0x00, // trailing byte
            0x05, // binary
                0x44,0x61,0x74,0x61, // Data
                0x00, // trailing byte
            0x06,0x00,0x00,0x00, // number of bytes
                0x80, // subtype
                0x66,0x6f,0x6f,0x62,0x61,0x72,
        0x00
    */

    ojson j = bson::decode_bson<ojson>(buffer);

    std::cout << "(2)\n" << pretty_print(j) << "\n\n";
    std::cout << "(3) " << j["Data"].tag() << "("  << j["Data"].ext_tag() << ")\n\n";

    // Get binary value as a std::vector<uint8_t>
    auto bstr2 = j["Data"].as<std::vector<uint8_t>>();
    assert(bstr2 == bstr);

    std::vector<uint8_t> buffer2;
    bson::encode_bson(j, buffer2);
    assert(buffer2 == buffer);
}

Output:

(1)
27,00,00,00,02,48,65,6c,6c,6f,00,06,00,00,00,57,6f,72,6c,64,00,05,44,61,74,61,00,06,00,00,00,80,66,6f,6f,62,61,72,00

(2)
{
    "Hello": "World",
    "Data": "Zm9vYmFy"
}

(3) ext(128)

See also

byte_string_view