nlohmann::basic_json::to_bson

// (1)
static std::vector<std::uint8_t> to_bson(const basic_json& j);

// (2)
static void to_bson(const basic_json& j, detail::output_adapter<std::uint8_t> o);
static void to_bson(const basic_json& j, detail::output_adapter<char> o);

BSON (Binary JSON) is a binary format in which zero or more ordered key/value pairs are stored as a single entity (a so-called document).

1. Returns a byte vector containing the BSON serialization.
2. Writes the BSON 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

Return value

1. BSON serialization as a byte vector
2. (none)

Exception safety

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

Exceptions

• Throws type_error.317 if the top-level type of the JSON value is not an object; example: "to serialize to BSON, top-level type must be object, but is string"
• Throws out_of_range.409 if a key in the JSON object contains a null byte (code point U+0000); example: "BSON key cannot contain code point U+0000 (at byte 2)"

Complexity

Linear in the size of the JSON value j.

Examples

Example

The example shows the serialization of a JSON value to a byte vector in BSON format.

#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>

using json = nlohmann::json;
using namespace nlohmann::literals;

int main()
{
    // create a JSON value
    json j = R"({"compact": true, "schema": 0})"_json;

    // serialize it to BSON
    std::vector<std::uint8_t> v = json::to_bson(j);

    // print the vector content
    for (auto& byte : v)
    {
        std::cout << "0x" << std::hex << std::setw(2) << std::setfill('0') << (int)byte << " ";
    }
    std::cout << std::endl;
}

Output:

0x1b 0x00 0x00 0x00 0x08 0x63 0x6f 0x6d 0x70 0x61 0x63 0x74 0x00 0x01 0x10 0x73 0x63 0x68 0x65 0x6d 0x61 0x00 0x00 0x00 0x00 0x00 0x00

See also

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

Version history

• Added in version 3.4.0.