属性错误：运行 sub_file.py 时，“NoneType”对象没有属性“recv”

Question

当我运行 sub_file.py 程序时，出现如下错误：

AttributeError: 'NoneType' object has no attribute 'recv'

这是 sub_file.py 代码：

import time
import paho.mqtt.client as mqtt #import the client1
import base64

broker_address="mqtt.eclipseprojects.io"

port = 1883
client = mqtt.Client("P2") #create new instance

client.connect(broker_address,port) #connect to broker

def on_message(cln, obj, msg):
  print("new message")
  data = msg.payload.decode()
  msg = str(data)
  img = msg.encode('ascii')
  with open('iris.jpg', 'wb') as fd:
    final_data = base64.b64decode(img)
    fd.write(final_data)
    fd.close()

def on_subscribe(client, userdata, mid, granted_qos):
  print("subscribe success")

client.subscribe("photo_topic_file")


client.on_subscribe = on_subscribe
print("Subscribing...")
client.loop_start()

client.on_message = on_message

client.loop_forever()

这是 pub_file.py 代码：

import paho.mqtt.client as mqtt
import base64
import time

broker_address="mqtt.eclipseprojects.io"

port = 1883
client = mqtt.Client("P1")


f = open("data.jpg", "rb")
isi_file = f.read()
convert_result_ke_base64 = base64.b64encode(isi_file)


client.connect(broker_address, port)
client.loop_start()
result = client.publish("photo_topic_file", convert_result_ke_base64)

if result[0] == 0:
    print("publish success")
else:
    print("publish failed")
    
time.sleep(5)
client.loop_stop()

当我运行 pub_file.py 时，程序正常工作，但是当我运行 sub_file.py 时，它显示错误

有人可以解决这个问题吗？

Answer 1

client.on_subscribe = on_subscribe
print("Subscribing...")
client.loop_start()

client.on_message = on_message

client.loop_forever()

您正在启动两个消息循环：

• 一个带有

  client.loop_start()

• 另一个带有

  client.loop_forever()

这会导致问题，因为编写代码时假设只有一个消息循环将运行。

解决此问题的最简单方法是删除

client.loop_start()

。

请注意，最好从

subscribe

调用

on_connect

，如“入门”所示。我还建议在调用

connect

之前设置回调（在启动循环后设置

on_message

可能会导致消息丢失）。