预期的字符串或缓冲区Python

Question

I'm really new to python, it's the first time I'm writing it actually. And I'm creating a program that gets the number of views on a Twitch.tv stream, but I'm getting an error Expected string or buffer Python when I'm calling this function

 def getURL():
  output = subprocess.Popen(["livestreamer", "twitch.tv/streamname", "-j"], stdout=subprocess.PIPE).communicate()[1]
  return json.loads(output)["streams"]["worst"]["url"]

I'm calling the function from here:

urls = []

urls.append(getURL())

What am I doing wrong? I've been trying to figure this one out for ages... And if anybody knows how to fix this, I'd be the happiest man alive ;)

Thanks in advance.

EDIT:

This is all the code I have.

import requests
import subprocess
import json
import sys
import threading
import time

urls = []
urlsUsed = []

def getURL():
output = subprocess.Popen(["livestreamer", "twitch.tv/hemzk", "-j"],       stdout=subprocess.PIPE).communicate()[1]
return json.loads(output)["streams"]["worst"]["url"]

def build():

global numberOfViewers

  urls.append(getURL())

And I'm getting the error at return json.loads(output)["streams"]["worst"]["url"]

Answer 1

Change

output = subprocess.Popen(["livestreamer", "twitch.tv/streamname", "-j"],
                          stdout=subprocess.PIPE).communicate()[1] 

to

output = subprocess.Popen(["livestreamer", "twitch.tv/streamname", "-j"],
                          stdout=subprocess.PIPE).communicate()[0] 

(Change 1 to 0).

More detailed explanation of your problem follows. Popen.communicate returns a tuple stdout, stderr . Here, it looks like you are interested in stdout (index 0), but you are picking out stderr (index 1). stderr is None here because you have not attached a pipe to it. You then try to parse None using json.loads() which expected a str or a buffer object.

If you want stderr output, you must add stderr=subprocess.PIPE to your Popen constructor call.