python - 循环10小时后出现KeyError

我在下面的脚本中得到以下KeyError，它已经在15秒的循环中运行了大约10个小时。为什么每15秒运行一次的关键错误在10小时内只出现一次？
错误：

Traceback (most recent call last):

  File "C:\venderFix.py", line 33, in <module>

    if j['results']:

KeyError: 'results'

代码：

import json
import urllib
from pprint import pprint
import time
from arduino import Arduino

vendtime = 0.2
delayTime = 15
searchTerm = 'happy'

A = Arduino('COM3') #This will need to be COM3
A.output([12]) #Output on pin 12

countTweet = 0
#To test Twitter for consistancy
tweet= 0
noTweet= 0



#the infinate loop
while True:

    #j contains the JSON we load from the URL
    j =json.loads(urllib.urlopen('http://search.twitter.com/search.json?q='+searchTerm+'&result_type=recent&rpp=1&filter:retweets').read())

    #Debug JSON from twitter (for faults on the Twitter end or possible GET limit id below 15 seconds per request)
    #pprint(j) #needed for debugging only

    #find the text and the tweet id
    if j['results']:
        text = j['results'][0]['text']
        id = j['results'][0]['id']
        #how many times the Json is complete
        tweet+= 1
    else:
        #How many times the Json is incomplete (sometimes twitter malfunctions. About 0.1 in 100 are broken)
        noTweet += 1

    #print the text and id to the screen
    pprint(text) #needed for debugging only
    pprint(id)   #needed for debugging only

    #to get the existing tweet from before we power on, if the first ID has been stored already (count == 1)
    if countTweet != 0:  #if countTweet is not equal to 0 then it's not the first tweet
        #pprint ("new loop") #needed for debugging only

        #if lastID is not equal to ID
        if lastID != id:
        #Tell Arduino to Vend
            #pin 12 HIGH
            A.setHigh(12)
            #Sleep for the time specified in vendtime
            time.sleep(vendtime)
            #pin 12 LOW
            A.setLow(12)
            #Display the tweet that triggered the vend
            #pprint(text) #needed for debugging only
            #pprint(id)   #needed for debugging only
            #Make lastID equal to ID so that next time we can compare it
            lastID = id
            #pprint ('lastID updated') #needed for debugging only
        #if no new tweets, print
        else:  #needed for debugging only
            pprint ('no new tweets') #needed for debugging only
    #If it's the first loop, confirm by printing to the screen
    else:
        pprint("First loop complete")
        pprint(text)
        pprint(id)
        lastID = id
        pprint(lastID)
        countTweet += 1 #Add 1 to countTweet

    pprint ('Number of Tweets')
    pprint (countTweet)
    pprint('Working JSON')
    pprint(tweet)
    pprint('Broken JSON')
    pprint(noTweet)

    pprint('waiting')
    time.sleep(delayTime)

最佳答案

因为在那个迭代中，results中没有键。
测试字典中是否有密钥的正确方法是：

if 'result' in j:
     ....

如果还想检查它的值是否不dict或任何其他错误值，则：

if 'result' in j and j['result']:
    ...

另一个假设是，与调用服务的事实相关的假设是，服务器偶尔会返回一条错误消息。
如果发生这种情况，JSON结构可能不是您期望的那样，您应该检查文档是否对此有任何说明，并相应地处理它。

关于python - 循环10小时后出现KeyError，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/16479752/