insert.md

jsoncons::jsonpointer::insert

Adds a json value.

Header

#include <jsoncons_ext/jsonpointer/jsonpointer.hpp>

template<class J>
void insert(J& target, const typename J::string_view_type& path, const J& value); // (1) 

template<class J>
void insert(J& target, const typename J::string_view_type& path, const J& value, std::error_code& ec); // (2) 

Inserts a value into the target at the specified path, if the path doesn't specify an object member that already has the same key.

• If path specifies an array index, a new value is inserted into the array at the specified index.

• If path specifies an object member that does not already exist, a new member is added to the object.

Return value

None

Exceptions

(1) Throws a jsonpointer_error if insert fails.

(2) Sets the std::error_code& to the jsonpointer_error_category if insert fails.

Examples

Add a member to a target location that does not already exist

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

using namespace jsoncons;

int main()
{
    json target = json::parse(R"(
        { "foo": "bar"}
    )");

    std::error_code ec;
    jsonpointer::insert(target, "/baz", json("qux"), ec);
    if (ec)
    {
        std::cout << ec.message() << std::endl;
    }
    else
    {
        std::cout << target << std::endl;
    }
}

Output:

{"baz":"qux","foo":"bar"}

Insert an element to the second position in an array

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

using namespace jsoncons;

int main()
{
    json target = json::parse(R"(
        { "foo": [ "bar", "baz" ] }
    )");

    std::error_code ec;
    jsonpointer::insert(target, "/foo/1", json("qux"), ec);
    if (ec)
    {
        std::cout << ec.message() << std::endl;
    }
    else
    {
        std::cout << target << std::endl;
    }
}

Output:

{"foo":["bar","qux","baz"]}

Insert a value at the end of an array

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

using namespace jsoncons;

int main()
{
    json target = json::parse(R"(
        { "foo": [ "bar", "baz" ] }
    )");

    std::error_code ec;
    jsonpointer::insert(target, "/foo/-", json("qux"), ec);
    if (ec)
    {
        std::cout << ec.message() << std::endl;
    }
    else
    {
        std::cout << target << std::endl;
    }
}

Output:

{"foo":["bar","baz","qux"]}

Attempt to insert object member at a location that already exists

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

using namespace jsoncons;

int main()
{
    json target = json::parse(R"(
        { "foo": "bar", "baz" : "abc"}
    )");

    std::error_code ec;
    jsonpointer::insert(target, "/baz", json("qux"), ec);
    if (ec)
    {
        std::cout << ec.message() << std::endl;
    }
    else
    {
        std::cout << target << std::endl;
    }
}

Output:

Key already exists

Attempt to insert value to a location in an array that exceeds the size of the array

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

using namespace jsoncons;

int main()
{
    json target = json::parse(R"(
    { "foo": [ "bar", "baz" ] }
    )");

    std::error_code ec;
    jsonpointer::insert(target, "/foo/3", json("qux"), ec);
    if (ec)
    {
        std::cout << ec.message() << std::endl;
    }
    else
    {
        std::cout << target << std::endl;
    }
}

Output:

Index exceeds array size