qingfengxia / pybind11_json

automatic conversion nlohmann::json and python object using pybind11

pybind11_json

Automatic conversion between nlohmann::json and pybind11::object

pybind11_json is an nlohmann::json to pybind11 bridge, it allows you to automatically convert nlohmann::json to py::object and the other way around:

#include "pybind11_json/pybind11_json.hpp"

#include "nlohmann/json.hpp"

#include "pybind11/pybind11.h"

namespace py = pybind11;
namespace nl = nlohmann;
using namespace pybind11::literals;

py::object obj = py::dict("number"_a=1234, "hello"_a="world");

nl::json j = obj;  // Automatic py::object->nl::json conversion
py::object o = j;  // Automatic nl::json->py::object conversion

conversion between nl::json and python dict object

C++ functions in test/pybind11_json_module.cpp

void print_pyobject_as_json(nlohmann::json s) {
    std::cout << "print_pyobject_as_json(): " << s << std::endl;
}
nlohmann::json return_json_as_pyobject() {
    nlohmann::json j = {{"value", 1}};
    std::cout << "return_json_as_pyobject() : "  << j<< std::endl;
    return j;
}

pybind11 binding code, see more in test/pybind11_json_module.cpp

m.def("print_pyobject_as_json", &print_pyobject_as_json, "pass py::object to c++");
m.def("return_json_as_pyobject", &return_json_as_pyobject, "get py::object from c++");

on python side, see test/test_pybind11_json.py

import pyjson
pyjson.print_pyobject_as_json({"value": 2})
dd = pyjson.return_json_as_pyobject()
print(dd)

Installation

Using conda

You can install pybind11_json using conda

conda install -c conda-forge pybind11 nlohmann_json pybind11_json

From sources

We encourage you to use conda for installing dependencies, but it is not a requirement for pybind11_json to work

conda install cmake nlohmann_json pybind11 -c conda-forge

Then you can install the sources

cmake -D CMAKE_INSTALL_PREFIX=your_conda_path
make install

Header only usage

Download the "pybind11_json.hpp", "json.hpp" single file into your project, and install/download pybind11 or use as git submodule.

Check header include path for json.hpp and pybind11, then you are ready to go.

Run tests

You can compile and run tests locally doing

cmake -D CMAKE_INSTALL_PREFIX=$CONDA_PREFIX -D DOWNLOAD_GTEST=ON ..
make
./test/test_pybind11_json

Dependencies

pybind11_json depends on

• pybind11
• nlohmann_json

pybind11_json	nlohmann_json	pybind11
master	>=3.2.0,<4.0	>=2.2.4,<3.0
0.2.3	>=3.2.0,<4.0	>=2.2.4,<3.0
0.2.2	>=3.2.0,<4.0	>=2.2.4,<3.0
0.2.1	>=3.2.0,<4.0	>=2.2.4,<3.0
0.2.0	>=3.2.0,<4.0	>=2.2.4,<3.0
0.1.0	>=3.2.0,<4.0	>=2.2.4,<3.0

License

We use a shared copyright model that enables all contributors to maintain the copyright on their contributions.

This software is licensed under the BSD-3-Clause license. See the LICENSE file for details.