replace.md

jsoncons::jsonpointer::replace

#include <jsoncons_ext/jsonpointer/jsonpointer.hpp>

template <typename Json,typename T>
void replace(Json& target, 
             const basic_json_pointer<Json::char_type>& location, 
             T&& value, 
             bool create_if_missing = false);                      (1)

template <typename Json,typename T>
void replace(Json& target, 
             const basic_json_pointer<Json::char_type>& location, 
             T&& value, 
             std::error_code& ec);                                 (2)

template <typename Json,typename T>
void replace(Json& target, 
             const basic_json_pointer<Json::char_type>& location, 
             T&& value, 
             bool create_if_missing, 
             std::error_code& ec);                                 (3)

template <typename Json,typename StringSource,typename T>
void replace(Json& target, 
             const StringSource& location_str, 
             T&& value, 
             bool create_if_missing = false);                      (4)

template <typename Json,typename StringSource,typename T>
void replace(Json& target, 
             const StringSource& location_str, 
             T&& value, 
             std::error_code& ec);                                 (5)

template <typename Json,typename StringSource,typename T>
void replace(Json& target, 
             const StringSource& location_str, 
             T&& value, 
             bool create_if_missing, 
             std::error_code& ec);                                 (6)

Replaces the value at the location specified by location with a new value.

If create_if_missing is false, the target location must exist for the replacement to succeed. If create_if_missing is true, and if the target location specifies object members that do not already exist, the missing objects and members are added.

Parameters

target	JSON value
location	A basic_json_pointer
location_str	A JSON Pointer provided as a string, string view, or C-string
value	Replacement value
create_if_missing (since 0.162.0)	Create key-object pairs when object key is missing
ec	out-parameter for reporting errors in the non-throwing overload

Return value

None

Exceptions

(1) Throws a jsonpointer_error if replace fails.

(2) Sets the out-parameter ec to the jsonpointer_error_category if replace fails.

Examples

Replace an object value

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

using jsoncons::json;
namespace jsonpointer = jsoncons::jsonpointer;

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

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

Output:

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

Replace an array value

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

using jsoncons::json;
namespace jsonpointer = jsoncons::jsonpointer;

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

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

Output:

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

Replace a value at a location after creating objects when missing object keys

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

using jsoncons::json;
namespace jsonpointer = jsoncons::jsonpointer;

int main()
{
    std::vector<std::string> keys = {"foo","bar","baz"};

    jsonpointer::json_pointer location;
    for (const auto& key : keys)
    {
        location /= key;
    }

    json doc;
    jsonpointer::replace(doc, location, "str", true);

    std::cout << pretty_print(doc) << "\n\n";
}

Output:

{
    "foo": {
        "bar": {
            "baz": "str"
        }
    }
}