JsonObject is a C++23 library built on Boost.JSON for reading and modifying nested JSON values using slash-separated key paths.

• Core library:
  • include/json_object.h
  • include/json_key_path.h
  • include/json_types.h
  • src/json_object.cc
  • src/json_key_path.cc
• Unit tests with GoogleTest in test/
• CMake build based on shared settings from cmake-common/

• Access nested JSON values with string paths like user/profile/name
• Access array items with index keys like [0], [1]
• Use special array symbols:
  • [^] first element (or prepend on set)
  • [$] last element (or append on set)
• Optional default values for safe reads
• Optional force=true writes to create compatible intermediate containers
• File I/O helpers:
  • load(filename)
  • write(filename, indent)

• Segments are separated by /
• Object keys are plain strings, for example: settings/theme
• Array indices are bracketed, for example: users/[0]/name
• Valid index symbols: [0], [1], ..., [^], [$]
• Invalid string keys include empty strings, whitespace-only strings, numeric-only strings, or keys containing [, ], \n, \r

#include <dkyb/json_object.h>

using util::JsonObject;

JsonObject obj(R"({"user":{"name":"Ada","age":36}})");

obj.set("user/name", "Ada Lovelace");
auto name = obj.get("user/name");

#include <dkyb/json_object.h>

using util::JsonObject;

JsonObject obj(R"({"user":{"name":"Ada"}})");

// Missing key in a compatible object path -> returns default
auto city = obj.get("user/city", "unknown");

// Incompatible path still throws (object vs array mismatch)
// obj.get("user/[0]", "fallback");

#include <dkyb/json_object.h>

using util::JsonObject;

JsonObject arr(R"([1,2,3])");

arr.set("[^]", 0);  // prepend -> [0,1,2,3]
arr.set("[$]", 4);  // append  -> [0,1,2,3,4]

auto first = arr.get("[^]");
auto last  = arr.get("[$]");

#include <dkyb/json_object.h>

using util::JsonObject;

JsonObject obj("{}");

// Without force this would throw due to missing path/container
obj.set("a/[0]/name", "node-0", true);
// Result is compatible structure created on demand

#include <dkyb/json_key_path.h>
#include <dkyb/json_object.h>

util::JsonObject obj(R"({"items":[{"id":7}]})");
util::JsonKeyPath path("items/[0]/id");

auto id = obj.get(path);

#include <dkyb/json_object.h>

util::JsonObject obj;
obj.load("input.json");
obj.set("meta/version", 2, true);
obj.write("output.json", 2);  // pretty-print with 2-space indentation

• CMake
• C++23 compiler
• Boost (Boost.JSON component)
• GoogleTest (for tests)

git clone --recurse-submodules -j "$(nproc)" git@github.com:kingkybel/JsonObject.git
cd JsonObject
cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug
cmake --build build --parallel "$(nproc)"

ctest --test-dir build --output-on-failure
# or: ./build/Debug/bin/run_tests

INSTALL_PREFIX=/usr
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX="${INSTALL_PREFIX}"
cmake --build build --parallel "$(nproc)"
sudo cmake --install build

Headers are installed to ${INSTALL_PREFIX}/include/dkyb and the library to ${INSTALL_PREFIX}/lib.

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