json/api/basic_json/to_ubjson.md

nlohmann::basic_json::to_ubjson

// (1)
static std::vector<std::uint8_t> to_ubjson(const basic_json& j,
                                           const bool use_size = false,
                                           const bool use_type = false);

// (2)
static void to_ubjson(const basic_json& j, detail::output_adapter<std::uint8_t> o,
                      const bool use_size = false, const bool use_type = false);
static void to_ubjson(const basic_json& j, detail::output_adapter<char> o,
                      const bool use_size = false, const bool use_type = false);

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

1. Returns a byte vector containing the UBJSON serialization.
2. Writes the UBJSON 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, #!cpp false by default.

use_type (in)

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

Return value

1. UBJSON 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 other_error.502 if use_type is true and use_size is false.

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 UBJSON format.
 
```cpp
--8<-- "examples/to_ubjson.cpp"
```

Output:

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

See also

• from_ubjson create a JSON value from an input in UBJSON 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_bjdata create a BJData serialization of a JSON value

Version history

• Added in version 3.1.0.