python 2.7 socket communication with json

Question

I want to send/recv data through socket.

I use python 2.7 because of ROS(melodic) and also use python 3.6 because of tensorflow.

The dict data, for example {'key_name':[[1,2,3],[4,5,6]]} , is sent and encoded with JSONEncoder.encoder() .
The Client received the json data with loads() and resend it to the Server.
The Client uses python 2.7 and the Server uses python 3.6

def _send(socket, send_data):
    json_data = json.JSONEncoder().encode(send_data)
    socket.sendall(json_data)

def _recv(socket):
    recv_data = socket.recv(BUFSIZE)
    json_data = json.loads(recv_data, encoding="utf-8")

    return json_data

I have the error

  File "/usr/lib/python3.6/json/deoder.py", line 357, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 4097 (char 4096)

I need a python code which runs on both python 2.7 and 3.6.

Answer 1

The error is coming from json decoder.

json_data = json.loads(recv_data, encoding="utf-8"),

It is expected when your json data ( in your case the recv_data ) is not in proper format. Usually missing a comma ',' or something. For debugging I would suggest you to dump the data received at server, before going for json.loads()