ROS messages to JSON and back

ros2json.py

import os
import importlib
import rosidl_runtime_py
import json

def get_msg_type(type):
    symbol = os.path.basename(type)
    module = ".".join(os.path.split(os.path.dirname(type)))
    return getattr(importlib.import_module(module), symbol)

def __msg_to_dict(msg):
    return rosidl_runtime_py.message_to_ordereddict(msg)

def __dict_to_msg(type_name, values):
    instance = get_msg_type(type_name)()
    rosidl_runtime_py.set_message_fields(instance, values)
    return instance

def msg_to_json(msg):
    return json.dumps(__msg_to_dict(msg))

def json_to_msg(type_name, json_string):
    return __dict_to_msg(type_name, json.loads(json_string))

# Example

Pose = get_msg_type('turtlesim/msg/Pose')
p = Pose()
p.x = 1.0
p.y = 2.0
p.x = 4.653351783752441
p.y = 5.970754623413086
p.theta = -0.9212489724159241
p.linear_velocity = 2.0
p.angular_velocity = 1.7999999523162842
json_string = msg_to_json(p)
q = json_to_msg('turtlesim/msg/Pose', json_string)
p == q