即使dict键中存在属性,getattr也会返回默认值

Question

我有一个包含一些json的文件,我加载并循环"servers"项并将它们传递给一个send_alert()方法(标记为"REDACTED"的项目不是真正的代码/输出):

"servers": [
  {
    "address": "smtp.gmail.com", 
    "encrypted-password": "Copy and Paste from 'password' after encryption.", 
    "login-name": false, 
    "port": 587, 
    "type": "email"
  }, 
  {
    "address": "smtp.mail.yahoo.com", 
    "encrypted-password": "<REDACTED>", 
    "login-name": "<REDACTED>@yahoo.com", 
    "port": 587, 
    "type": "email"
  }]

我希望跳过gmail项,因为它应该为'login-name'呈现False或None ...所以我真的只是处理yahoo项:

def send_alert(self, server, message, email):
    print(json.dumps(server, encoding=self.encoding,
                                 sort_keys=True, indent=2))
    print(type(server))
    print(server["login-name"])
    username = getattr(server, "login-name", None)
    enc_pass = getattr(server, "encrypted-password", None)
    address = getattr(server, "password", None)
    port = getattr(server, "port", None)
    server_type = getattr(server, "type", None)
    mess = message
    if not username:
        print(username)
        self.log.warn("incorrectly configured alert!\n:%s",
                      json.dumps(server, encoding=self.encoding,
                                 sort_keys=True, indent=2))
        return False
    if server_type.lower() == "email":
        self.send_email(username, enc_pass, address, port, mess, email)
    else:
        self.log.debug("unknown server type listed in Alerts/servers")

当send_alert被调用时,我收到以下的输出:

{
  "address": "smtp.mail.yahoo.com",
  "encrypted-password": <REDACTED>,
  "login-name": "<REDACTED>@yahoo.com",
  "port": 587,
  "type": "email"
}
<type 'dict'>
<REDACTED>@yahoo.com
None
[11:35:39] [Wrapper.py/WARNING]: incorrectly configured alert!
:{
  "address": "smtp.mail.yahoo.com",
  "encrypted-password": <REDACTED>,
  "login-name": "<REDACTED>@yahoo.com",
  "port": 587,
  "type": "email"
}

我想使用getattr,而不是testing(if "login-name" in server:)或try-exceptpting值.我在其他案例中成功完成了这项工作.然而,这让我很难过. getattr()即使有效的关键项似乎存在,也会返回默认值None.怎么了？

我尝试了一些建议的"可能已经有你答案的问题",没有人给我任何帮助.这个似乎很有希望,但要么从未回答,要么答案(由提问者提供)不适用于我的情况:Python 3 AttributeError即使属性存在 (即,我尝试深入复制单个字典项服务器,然后再将其传递给send_alert)

Python 2和3的输出相同.

Answer 1

getattr 获取对象的属性,而不是与映射中的键关联的值.

getattr(server, 'login-name', None)正在尝试访问属性server.login-name,而不是值server['login-name']

您可以改为使用该dict.get方法

server.get('login-name', None)