Sanic + MessagePack

client.py

import requests
from json import dumps, loads
from msgpack import packb, unpackb

data = {'say': 'hello, world!'}
headers_msgpack = {'Content-Type': 'application/msgpack'}
headers_json = {'Content-Type': 'application/json'}

r = requests.post('http://localhost:8000/', data=packb(data), headers=headers_msgpack)
print(unpackb(r.content))

r = requests.post('http://localhost:8000/', data=dumps(data), headers=headers_json)
print(loads(r.content))

sanic_msgpack.py

from sanic.response import HTTPResponse
from sanic.request import Request
from sanic.exceptions import InvalidUsage

from msgpack import packb, unpackb

MSGPACK_MIME_TYPE = 'application/msgpack'
# https://github.com/msgpack/msgpack/issues/194

class MsgPackRequest(Request):
    __slots__ = ('parsed_msgpack',)

    def __init__(self, url_bytes, headers, version, method, transport):
        self.parsed_msgpack = None
        super().__init__(url_bytes, headers, version, method, transport)

    @property
    def msgpack(self):
        if self.parsed_msgpack is None:
            try:
                self.parsed_msgpack = unpackb(self.body)
            except Exception:
                raise InvalidUsage('Failed when parsing body as msgpack')

        return self.parsed_msgpack


def msgpack(body, status=200, headers=None,
            content_type=MSGPACK_MIME_TYPE, **kwargs):
    """
    Returns response object with body in MessagePack format.
    :param body: Response data.
    :param status: Response code.
    :param headers: Custom Headers.
    :param content_type: the content type (string) of the response.
    :param kwargs: Remaining arguments that are passed to the msgpack encoder.
    """
    return HTTPResponse(body_bytes=packb(body, **kwargs), status=status,
                        headers=headers, content_type=content_type)

server.py

from sanic import Sanic
from sanic import response

from sanic_msgpack import MsgPackRequest, msgpack
response.msgpack = msgpack

app = Sanic(request_class=MsgPackRequest)

@app.route("/", methods=['POST'])
async def test(request):
    if request.content_type == 'application/msgpack':
        return response.msgpack({'say': 'hello, msgpack!'})
    elif request.content_type == 'application/json':
        return response.json({'say': 'hello, json!'})

if __name__ == "__main__":
    app.run(host='localhost', port=8000)