json/api/basic_json/to_msgpack.md

nlohmann::basic_json::to_msgpack

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

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

Serializes a given JSON value j to a byte vector using the MessagePack serialization format. MessagePack is a binary serialization format that aims to be more compact than JSON itself, yet more efficient to parse.

1. Returns a byte vector containing the MessagePack serialization.
2. Writes the MessagePack 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. MessagePack 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 out_of_range.412 if the length of a string, binary value, array, or object exceeds 4294967295, the maximum MessagePack can store; example: "MessagePack length 4294967296 exceeds maximum of 4294967295"
• Throws out_of_range.415 if the subtype of a binary value exceeds 255, the maximum of the MessagePack ext type; example: "subtype 70000 is too large for the MessagePack ext type (max 255)"

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 MessagePack format.
 
```cpp
--8<-- "examples/to_msgpack.cpp"
```

Output:

```json
--8<-- "examples/to_msgpack.output"
```

See also

• from_msgpack create a JSON value from an input in MessagePack format
• to_cbor create a CBOR 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
• to_bjdata create a BJData serialization of a JSON value

Version history

• Added in version 2.0.9.
• Throws out_of_range.412 and out_of_range.415 since version 3.13.0.