jmespath.cpp is a C++ implementation of JMESPath, a query language for JSON. It can be used to extract and transform elements of a JSON document.
Input JSON document:
{
"locations": [
{"name": "Seattle", "state": "WA"},
{"name": "New York", "state": "NY"},
{"name": "Bellevue", "state": "WA"},
{"name": "Olympia", "state": "WA"}
]
}JMESPath expression:
locations[?state == 'WA'].name | sort(@) | {WashingtonCities: join(', ', @)}
Result of evaluating the expression:
{"WashingtonCities": "Bellevue, Olympia, Seattle"}For more examples take a look at the JMESPath Tutorial or the JMESPath Examples pages.
To use the public functions and classes of jmespath.cpp you should include the header file #include <jmespath/jmespath.h>. The public interface is declared in the jmespath namespace.
#include <iostream> #include <jmespath/jmespath.h> namespace jp = jmespath; int main(int argc, char *argv[]) { auto data = R"({ "locations": [ {"name": "Seattle", "state": "WA"}, {"name": "New York", "state": "NY"}, {"name": "Bellevue", "state": "WA"}, {"name": "Olympia", "state": "WA"} ] })"_json; jp::Expression expression = "locations[?state == 'WA'].name | sort(@) | " "{WashingtonCities: join(', ', @)}"; std::cout << jp::search(expression, data) << std::endl; return 0; }
http://robertmrk.github.io/jmespath.cpp
To build, install and use the library you must have CMake installed, version 3.8 or later.
jmespath.cpp needs a compiler that supports at least the c++14 standard. The currently supported and tested compilers are:
- g++ versions: 6, 7, 8
- Clang versions: 4.0, 5.0, 6.0, 7
- XCode versions: 9.0, 9.3, 10.1
- Visual Studio 2017
- boost version 1.65 or later
- nlohmann_json version 3.4.0 or later
To get the source code of the library either clone it from github
git clone https://github.com/robertmrk/jmespath.cpp.git
or download the latest release and extract it.
In the terminal change the current directory to the location of the source code
cd <path_to_source>/jmespath.cpp
Generate the project or makefiles for the build system of your choice with CMake, then build and install the library:
mkdir build cd build cmake .. -G"Unix Makefiles" -DCMAKE_BUILD_TYPE=Release -DJMESPATH_BUILD_TESTS=OFF sudo cmake --build . --target install
To use the library in your CMake project you should find the library with find_package and link your target with jmespath::jmespath:
cmake_minimum_required(VERSION 3.8) project(example) find_package(jmespath 0.1.0 CONFIG REQUIRED) add_executable(${PROJECT_NAME} main.cpp) target_link_libraries(${PROJECT_NAME} jmespath::jmespath) target_compile_features(${PROJECT_NAME} PUBLIC cxx_std_14)
If you are using Conan to manage your dependencies, then add jmespath.cpp/x.y.z@robertmrk/stable to your conanfile.py's requires, where x.y.z is the release version you want to use.
Please file issues here if you experience problems with the packages.