如何解决 Ubuntu 中的 Json 解码错误

Question

I am running python script on Window 10. In the python script, I am using json library. When I run the same script on Ubuntu 20.04(running on VMware), I do see json decode error happening. This behaviour I dont see when I run in Windows 10.

The following is the error I do get when I run the script in Ubuntu

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python3.8/threading.py", line 932, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.8/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "uiControl.py", line 83, in getTcpData
    self.taskObj = json.loads(data.decode('utf-8'))
  File "/usr/lib/python3.8/json/__init__.py", line 357, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.8/json/decoder.py", line 340, in decode
    raise JSONDecodeError("Extra data", s, end)
json.decoder.JSONDecodeError: Extra data: line 5 column 2 (char 73)

In function on_message, I am printing the data received. The following is the data I receive : b'{"code":"101","user":"ssmr","evNumber":"TS15EC1100"}'

I call the function addToTaskQueue() to store the received data and then try to parse the data using function BackendParser()

def on_message(self,client, userdata, msg):
    print(msg.payload)
    self.taskObj = json.loads(msg.payload )
    self.taskObj["commType"]= "mqtt"
    self.taskObj["transactionType"]= "rx"        
    taskScheduler.addToTaskQueue(self.taskObj)

def BackendParser(msg):
    if(msg["code"] == "101"):
        Backend.userName = msg["user"]
        Backend.evNumber = msg["evNumber"]
        Backend.evChargeControl = "On"
        if(Backend.requestStatus == ""):
            Backend.requestStatus = "new"


class taskScheduler():
    global qTaskList

    qTaskList = queue.Queue()     
    def __init__(self):
        super().__init__()
        self.tcpCon = tcpServerClient("client")
        self.mqttCon = mqttComm()
        print("Initiated Task Scheduler class")

    @staticmethod
    def addToTaskQueue(item):
        if not qTaskList.full():
            #print("Task added")
            qTaskList.put(item)

    def executeFromTaskQueue(self):
        if not qTaskList.empty():
            item = qTaskList.get()
            if("mqtt" == item["commType"]):
                if("tx" == item["transactionType"]):
                    pubTopic = item["topic"]
                    del item["commType"]
                    del item["transactionType"]
                    del item["topic"]
                    self.mqttCon.mqttSend(item,pubTopic)
                elif("rx" == item["transactionType"]):
                    BackendParser(item)
            elif("tcp" == item["commType"]):
                if("tx" == item["transactionType"]):
                    del item["commType"]
                    del item["transactionType"]
                    tcpServerClient.sendTcpData(item)
                elif("rx" == item["transactionType"]):
                    BackendParser(item)

Answer 1

I figured out the error I was using the following function getTcpData to receive the data. I tried printing the data as received and noticed that there were \\n characters in the message received.This was not issue when the script was executed in Windows 10. I now added the routine to remove the \\n character and now it works fine in Ubuntu.

def getTcpData(self):  
    print("Waiting for tcp data")
    while True:
        if(tcpServerClient.clientsocket != None):
            data=tcpServerClient.clientsocket.recv(1024)
            if data:
                print(data)
                self.taskObj = json.loads(data.decode('utf-8'))
                self.taskObj["commType"]= "tcp"
                self.taskObj["transactionType"]= "rx"
                taskScheduler.addToTaskQueue(self.taskObj)