basic_json::from_bson¶
// (1)
template<typename InputType>
static basic_json from_bson(InputType&& i,
const bool strict = true,
const bool allow_exceptions = true);
// (2)
template<typename IteratorType>
static basic_json from_bson(IteratorType first, IteratorType last,
const bool strict = true,
const bool allow_exceptions = true);
Deserializes a given input to a JSON value using the BSON (Binary JSON) serialization format.
- Reads from a compatible input.
- Reads from an iterator range.
Template parameters¶
InputType-
A compatible input, for instance:
- an
std::istreamobject - a
FILEpointer - a C-style array of characters
- a pointer to a null-terminated string of single byte characters
- an object
objfor whichbegin(obj)andend(obj)produces a valid pair of iterators.
- an
IteratorType- a compatible iterator type
Parameters¶
i(in)- an input in BSON format convertible to an input adapter
first(in)- iterator to start of the input
last(in)- iterator to end of the input
strict(in)- whether to expect the input to be consumed until EOF (
trueby default) allow_exceptions(in)- whether to throw exceptions in case of a parse error (optional,
trueby default)
Return value¶
deserialized JSON value; in case of a parse error and allow_exceptions set to 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.
Complexity¶
Linear in the size of the input.
Example¶
Example
The example shows the deserialization of a byte vector in BSON format to a JSON value.
#include <iostream>
#include <iomanip>
#include <nlohmann/json.hpp>
using json = nlohmann::json;
int main()
{
// create byte vector
std::vector<uint8_t> v = {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
};
// deserialize it with BSON
json j = json::from_bson(v);
// print the deserialized JSON value
std::cout << std::setw(2) << j << std::endl;
}
Output:
{
"compact": true,
"schema": 0
}
Version history¶
- Added in version 3.4.0.