How to send a json object using tcp socket in python

Question

here is my python tcp client. I want to send a json object to the server.But I can't send the object using the sendall() method. how can I do this?

import socket
import sys
import json

HOST, PORT = "localhost", 9999

m ='{"id": 2, "name": "abc"}'
jsonObj = json.loads(m)


data = jsonObj

# Create a socket (SOCK_STREAM means a TCP socket)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

try:
    # Connect to server and send data
    sock.connect((HOST, PORT))
    sock.sendall(jsonObj)


    # Receive data from the server and shut down
    received = sock.recv(1024)
finally:
    sock.close()

print "Sent:     {}".format(data)
print "Received: {}".format(received)

When you say 'I can't send the object', do you see any error? Or is the program stuck? Have you verified that a TCP server is listening at localhost:9999? — AnishT
– AnishT, Commented Oct 2, 2016 at 13:55
server is listening. and the following error appears.. Traceback (most recent call last): File "C:/Users/Lochana/PycharmProjects/SocketClient/TCPClient.py", line 19, in <module> sock.sendall(jsonObj) File "C:\Python27\lib\socket.py", line 228, in meth return getattr(self._sock,name)(*args) TypeError: sendall() argument 1 must be string or buffer, not dict — Lochana Thenuwara
– Lochana Thenuwara, Commented Oct 2, 2016 at 14:24
In that case, you need to serialize dict to string. Or pass the object 'm' to sendall instead of 'jsonObj'. (What is Serialization - en.m.wikipedia.org/wiki/Serialization) — AnishT
– AnishT, Commented Oct 2, 2016 at 14:39

harry · Accepted Answer · 2020-04-21 18:19:01Z

9

Sending a dict with json like below worked in my program.

import socket
import sys
import json

HOST, PORT = "localhost", 9999

#m ='{"id": 2, "name": "abc"}'
m = {"id": 2, "name": "abc"} # a real dict.


data = json.dumps(m)

# Create a socket (SOCK_STREAM means a TCP socket)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

try:
    # Connect to server and send data
    sock.connect((HOST, PORT))
    sock.sendall(bytes(data,encoding="utf-8"))


    # Receive data from the server and shut down
    received = sock.recv(1024)
    received = received.decode("utf-8")

finally:
    sock.close()

print "Sent:     {}".format(data)
print "Received: {}".format(received)

edited Apr 21, 2020 at 18:19

answered Apr 21, 2020 at 18:10

harry

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Community · Accepted Answer · 2017-05-23 12:15:06Z

5

Skip the json.loads() part. Send the json object as the json string and load it from the string at the TCP client.

Also check: Python sending dictionary throught TCP

edited May 23, 2017 at 12:15

CommunityBot

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answered Oct 2, 2016 at 13:50

Moinuddin Quadri

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3 Comments

Moinuddin Quadri Over a year ago

No, you can not send the JSON object. You need to firstly serialize it

AnishT Over a year ago

@LochanaThenuwara Send and sendall methods of socket accept string as parameter. Hence, you need to send data as string. In this case, data is json. At client end, convert it to string and at server, convert the received string to json.

Yuseferi Over a year ago

when it's just a string returns TypeError: a bytes-like object is required, not 'str' and when using with json.loads returns TypeError: a bytes-like object is required, not 'dict'

Yuseferi · Accepted Answer · 2018-05-09 09:44:57Z

1

AS you can find out from Python sending dictionary through TCP it better convert the JSON object to a dictionary and using the following snippet

import json
data = json.load(open("data.json"))
 //or 
data = json.load('{"id": 2, "name": "abc"}')

type(data)
print(data[<keyFromTheJsonFile>])

You should serialize it with pickle:

import pickle
dict = {...}
tcp_send(pickle.dumps(dict))

And on the other end:

import pickle
dict = pickle.loads(tcp_recieve())

If the other end is not written in python, you can use a data serialization format, like xml, json or yaml.

answered May 9, 2018 at 9:44

Yuseferi

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