Python 索引器:列表索引超出范围(在查询结果中)
我在理解如何处理查询结果时遇到问题。我问了六个问题,但我还是不明白。我从以前的代码中复制,并以某种方式使其工作,但由于我不理解基本概念,如果我做一个小的更改,代码就会崩溃。如果你能告诉我你是如何想象这里发生的事情并向我解释的,我将不胜感激。多谢各位Python 索引器:列表索引超出范围(在查询结果中),python,google-app-engine,Python,Google App Engine,我在理解如何处理查询结果时遇到问题。我问了六个问题,但我还是不明白。我从以前的代码中复制,并以某种方式使其工作,但由于我不理解基本概念,如果我做一个小的更改,代码就会崩溃。如果你能告诉我你是如何想象这里发生的事情并向我解释的,我将不胜感激。多谢各位 class ReceiveEmail(InboundMailHandler): def receive(self, message): logging.info("Received email from %s" % messa
class ReceiveEmail(InboundMailHandler):
def receive(self, message):
logging.info("Received email from %s" % message.sender)
plaintext = message.bodies(content_type='text/plain')
for text in plaintext:
txtmsg = ""
txtmsg = text[1].decode()
logging.info("Body is %s" % txtmsg)
logging.info("CC email is %s" % ((message.cc).split(",")[1]))
query = User.all()
query.filter("userEmail =", ((message.cc).split(",")[1]))
results = query.fetch(1)
for result in results:
result.userScore += 1
um = results[0]
um.userScore = result.userScore
um.put()
据我所知,在这段代码中,查询从cc列表中获取第二个电子邮件地址并获取结果
然后我将userScore增加1
接下来,我想在数据存储中更新这个项目,所以我说
um = results[0]
um.userScore = result.userScore
um.put()
但这会产生索引超出范围的错误:
um = results[0]
IndexError: list index out of range
为什么??我想象结果[0]
是结果的第0项。为什么超出范围?我唯一能想到的是,列表可能是None
。但我不明白为什么。它必须具有已提取的1项
另外,如果我尝试通过将索引从[1]更改为[0]来测试第一个电子邮件地址
query.filter("userEmail =", ((message.cc).split(",")[0]))
那么我就不会得到索引器
我做错了什么
谢谢
编辑
见评论:
(message.cc).split(",")[0])
在电子邮件前面留了一个空格(从第二封电子邮件开始),因此查询与它们不匹配
>>> cc.split(",")
['cc12@example.com', ' cc13@example.com', ' cc13@example.com']
在逗号后添加空格修复了此问题:
>>> listcc = cc.split(", ")
>>> listcc
['cc12@example.com', 'cc13@example.com', 'cc13@example.com']
>>>
要理解代码,请将其分解并逐个查看:
class ReceiveEmail(InboundMailHandler):
def receive(self, message):
logging.info("Received email from %s" % message.sender)
# Get a list of CC addresses. This is basically a for loop.
cc_addresses = [address.strip() for address in message.cc.split(",")]
# The CC list goes with the message, not the bodies.
logging.info("CC email is %s" % (cc_addresses))
# Get and iterate over all of the *plain-text* bodies in the email.
plaintext = message.bodies(content_type='text/plain')
for text in plaintext:
txtmsg = ""
txtmsg = text[1].decode()
logging.info("Body is %s" % txtmsg)
# Setup a query object.
query = User.all()
# Filter the user objects to get only the emails in the CC list.
query.filter("userEmail IN", cc_addresses)
# But, only get at most 10 users.
users = query.fetch(10)
logging.info('Got %d user entities from the datastore.' % len(users))
# Iterate over each of the users increasing their score by one.
for user in users:
user.userScore += 1
# Now, write the users back to the datastore.
db.put(users)
logging.info('Wrote %d user entities.' % len(users))
我会调整你的模型结构。创建用户实体时,我会将密钥名称设置为电子邮件地址。您将能够使查询更加高效
一些参考资料:
- 要理解代码,请将其分解并逐个查看:
class ReceiveEmail(InboundMailHandler):
def receive(self, message):
logging.info("Received email from %s" % message.sender)
# Get a list of CC addresses. This is basically a for loop.
cc_addresses = [address.strip() for address in message.cc.split(",")]
# The CC list goes with the message, not the bodies.
logging.info("CC email is %s" % (cc_addresses))
# Get and iterate over all of the *plain-text* bodies in the email.
plaintext = message.bodies(content_type='text/plain')
for text in plaintext:
txtmsg = ""
txtmsg = text[1].decode()
logging.info("Body is %s" % txtmsg)
# Setup a query object.
query = User.all()
# Filter the user objects to get only the emails in the CC list.
query.filter("userEmail IN", cc_addresses)
# But, only get at most 10 users.
users = query.fetch(10)
logging.info('Got %d user entities from the datastore.' % len(users))
# Iterate over each of the users increasing their score by one.
for user in users:
user.userScore += 1
# Now, write the users back to the datastore.
db.put(users)
logging.info('Wrote %d user entities.' % len(users))
我会调整你的模型结构。创建用户实体时,我会将密钥名称设置为电子邮件地址。您将能够使查询更加高效
一些参考资料:
user11@example.com
和cc777@example.com
。我确保这两封电子邮件已经在数据库中,以便查询可以获取它们。但我刚刚再试了一次,索引0和1现在都不起作用。你能建议一些方法来检查查询看到了什么吗?谢谢。@Ignacio Vazquez Abrams:也许你是对的;查询似乎失败:if results:for result in results:result.userScore+=1 um=results[0]um.userScore=result.userScore um.put()其他:logging.info(“查询失败”)@Ignacio Vazquez Abrams:谢谢你的提示((message.cc).split(“,”[0])
在电子邮件前面留了一个空格,因此查询与它们不匹配;因此,在逗号后添加一个空格解决了这个问题:((message.cc).split(“,”[0])
您有多大把握首先要获取任何结果?是的,问得好。我正在从Dev控制台发送一封包含user11@example.com
和cc777@example.com
。我确保这两封电子邮件已经在数据库中,以便查询可以获取它们。但我刚刚再试了一次,索引0和1现在都不起作用。你能建议一些方法来检查查询看到了什么吗?谢谢。@Ignacio Vazquez Abrams:也许你是对的;查询似乎失败:if results:for result in results:result.userScore+=1 um=results[0]um.userScore=result.userScore um.put()其他:logging.info(“查询失败”)@Ignacio Vazquez Abrams:谢谢你的提示((message.cc).split(“,”[0])
在电子邮件前面留了一个空格,因此查询与它们不匹配;因此,在逗号后添加一个空格修复了这个问题:((message.cc).split(“,”[0])
你好罗伯特:感谢您的详细解释。这很有帮助。我研究了你提到的三个链接。特别感谢您修改和组织代码;现在它更有意义了。在put()
的情况下,我知道我们通过从userEmail
列过滤cc\u地址,从表User
中获取了10行。然后我们更新了userScore
,并通过db.put(users)
将更新的行写回数据存储。查看开发控制台的数据存储查看器;我明白了,app engine只知道更新userScore
。它实际上更新了实体上的所有属性,但因为我们只更改了userScore
,所以它是唯一更改的属性。你好,罗伯特:感谢您的详细解释。这很有帮助。我研究了你提到的三个链接。特别感谢您修改和组织代码;现在它更有意义了。在put()
的情况下,我知道我们通过从userEmail
列过滤cc\u地址,从表User
中获取了10行。然后我们更新了userScore
,并通过db.put(users)
将更新的行写回数据存储。查看开发控制台的数据存储查看器;我明白了,appengine只知道更新userScore
。它实际上更新了实体上的所有属性,但因为我们只更改了userScore
,所以它是唯一更改的属性。