json/docs/mkdocs/docs/api/basic_json/from_bjdata.md

nlohmann::basic_json::from_bjdata

// (1)
template<typename InputType>
static basic_json from_bjdata(InputType&& i,
                              const bool strict = true,
                              const bool allow_exceptions = true);
// (2)
template<typename IteratorType>
static basic_json from_bjdata(IteratorType first, IteratorType last,
                              const bool strict = true,
                              const bool allow_exceptions = true);

Deserializes a given input to a JSON value using the BJData (Binary JData) serialization format.

1. Reads from a compatible input.
2. Reads from an iterator range.

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

Template parameters

InputType

A compatible input, for instance:

• an std::istream object
• a FILE pointer
• a C-style array of characters
• a pointer to a null-terminated string of single byte characters
• a container obj for which begin(obj) and end(obj) produce a valid pair of iterators (as found via ADL or member functions, with semantics compatible to std::begin and std::end)

IteratorType

a compatible iterator type

Parameters

i (in)

an input in BJData format convertible to an input adapter

first (in)

iterator to the start of the input

last (in)

iterator to the end of the input

strict (in)

whether to expect the input to be consumed until EOF (#!cpp true by default)

allow_exceptions (in)

whether to throw exceptions in case of a parse error (optional, #!cpp true by default)

Return value

deserialized JSON value; in case of a parse error and allow_exceptions set to #!cpp false, the return value will be value_t::discarded. The latter can be checked with is_discarded.

Exception safety

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

Exceptions

• Throws parse_error.110 if the given input ends prematurely or the end of the file was not reached when strict was set to true
• Throws parse_error.112 if a parse error occurs
• Throws parse_error.113 if a string could not be parsed successfully
• Throws out_of_range.408 if the size of an optimized container or n-dimensional array cannot be represented by std::size_t

Complexity

Linear in the size of the input.

Examples

??? example

The example shows the deserialization of a byte vector in BJData format to a JSON value.
 
```cpp
--8<-- "examples/from_bjdata.cpp"
```

Output:

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

See also

• to_bjdata create a BJData serialization of a JSON value
• from_cbor create a JSON value from an input in CBOR format
• from_msgpack create a JSON value from an input in MessagePack format
• from_bson create a JSON value from an input in BSON format
• from_ubjson create a JSON value from an input in UBJSON format

Version history

• Added in version 3.11.0.
• Extended container support (1) to include types with lvalue-only ADL begin/end (matching std::begin/std::end semantics) in version 3.13.0.