jsonpointer.md

jsonpointer extension

The jsonpointer extension implements the IETF standard JavaScript Object Notation (JSON) Pointer

contains	Returns `true` if the json document contains the given json pointer
get	Get a value from a JSON document using Json Pointer path notation.
insert	Inserts a value in a JSON document using Json Pointer path notation, if the path doesn't specify an object member that already has the same key.
insert_or_assign	Inserts a value in a JSON document using Json Pointer path notation, or if the path specifies an object member that already has the same key, assigns the new value to that member.
remove	Removes a value from a JSON document using Json Pointer path notation.
replace	Replaces a value in a JSON document using Json Pointer path notation.

Examples

Example. Select author from second book

#include <jsoncons/json.hpp>
#include <jsoncons_ext/jsonpointer/jsonpointer.hpp>

using namespace jsoncons;

int main()
{
    json doc = json::parse(R"(
    [
      { "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      { "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "price": 12.99
      }
    ]
    )");

    // Using exceptions to report errors
    try
    {
        json result = jsonpointer::get(doc, "/1/author");
        std::cout << "(1) " << result << std::endl;
    }
    catch (const jsonpointer::jsonpointer_error& e)
    {
        std::cout << e.what() << std::endl;
    }

    // Using error codes to report errors
    std::error_code ec;
    json result = jsonpointer::get(doc, "/0/title", ec);

    if (ec)
    {
        std::cout << ec.message() << std::endl;
    }
    else
    {
        std::cout << "(2) " << result << std::endl;
    }
}

Output:

(1) "Evelyn Waugh"
(2) "Sayings of the Century"

jsonpointer::get may also be used to query the nested data items of a packed CBOR value.