nlohmann::basic_json::to_bjdata¶

// (1)
staticstd::vector<std::uint8_t>to_bjdata(constbasic_json&j,
constbooluse_size=false,
constbooluse_type=false,
constbjdata_version_tversion=bjdata_version_t::draft2);
// (2)
staticvoidto_bjdata(constbasic_json&j,detail::output_adapter<std::uint8_t>o,
constbooluse_size=false,constbooluse_type=false,
constbjdata_version_tversion=bjdata_version_t::draft2);
staticvoidto_bjdata(constbasic_json&j,detail::output_adapter<char>o,
constbooluse_size=false,constbooluse_type=false,
constbjdata_version_tversion=bjdata_version_t::draft2);

Serializes a given JSON value j to a byte vector using the BJData (Binary JData) serialization format. BJData aims to be more compact than JSON itself, yet more efficient to parse.

1. Returns a byte vector containing the BJData serialization.
2. Writes the BJData serialization to an output adapter.

The exact mapping and its limitations are described on a dedicated page.

Parameters¶

j (in)

JSON value to serialize

o (in)

output adapter to write serialization to

use_size (in)

whether to add size annotations to container types; optional, false by default.

use_type (in)

whether to add type annotations to container types (must be combined with use_size=true); optional, false by default.

version (in)

which version of BJData to use (see note on "Binary values" on BJData); optional, bjdata_version_t::draft2 by default.

Return value¶

1. BJData serialization as byte vector
2. (none)

Exception safety¶

Strong guarantee: if an exception is thrown, there are no changes in the JSON value.

Complexity¶

Linear in the size of the JSON value j.

Examples¶

#include<iostream>
#include<iomanip>
#include<nlohmann/json.hpp>
usingjson=nlohmann::json;
usingnamespacenlohmann::literals;
// function to print BJData's diagnostic format
voidprint_byte(uint8_tbyte)
{
if(32<byteandbyte<128)
{
std::cout<<(char)byte;
}
else
{
std::cout<<(int)byte;
}
}
intmain()
{
// create a JSON value
jsonj=R"({"compact": true, "schema": false})"_json;
// serialize it to BJData
std::vector<std::uint8_t>v=json::to_bjdata(j);
// print the vector content
for(auto&byte:v)
{
print_byte(byte);
}
std::cout<<std::endl;
// create an array of numbers
jsonarray={1,2,3,4,5,6,7,8};
// serialize it to BJData using default representation
std::vector<std::uint8_t>v_array=json::to_bjdata(array);
// serialize it to BJData using size optimization
std::vector<std::uint8_t>v_array_size=json::to_bjdata(array,true);
// serialize it to BJData using type optimization
std::vector<std::uint8_t>v_array_size_and_type=json::to_bjdata(array,true,true);
// print the vector contents
for(auto&byte:v_array)
{
print_byte(byte);
}
std::cout<<std::endl;
for(auto&byte:v_array_size)
{
print_byte(byte);
}
std::cout<<std::endl;
for(auto&byte:v_array_size_and_type)
{
print_byte(byte);
}
std::cout<<std::endl;
}

{i7compactTi6schemaF}
[i1i2i3i4i5i6i7i8]
[#i8i1i2i3i4i5i6i7i8
[$i#i812345678

See also¶

• from_bjdata create a JSON value from an input in BJData format
• to_cbor create a CBOR serialization of a JSON value
• to_msgpack create a MessagePack serialization of a JSON value
• to_bson create a BSON serialization of a JSON value
• to_ubjson create a UBJSON serialization of a JSON value

Version history¶

• Added in version 3.11.0.
• BJData version parameter (for draft3 binary encoding) added in version 3.12.0.