参数在传递给函数时从字典中消失

Question

在我的函数中，我从会话中读取用户的数据，并把它们存储在一个字典里。接着，我把这个字典传给了注册功能的'register'函数，但这个函数却莫名其妙地接收到了一个空的字典，导致出现了KeyError错误。我的数据去哪儿了呢？以下是调用'register'函数的代码：

data = request.session['temp_data']
email = data['email']

logging.debug(email)

password1 = data['password1']
userdata = {'email': email, 'password1': password1}

logging.debug(userdata)

backend = request.session['backend']

logging.debug(backend)

user = backend.register(userdata)

而'register'函数的代码（完整源代码在这里：http://bitbucket.org/ubernostrum/django-registration/src/tip/registration/backends/default/init.py）：

class DefaultBackend(object):
    def register(self, request, **kwargs):
        logging.debug("backend.register")
        logging.debug(kwargs)

        username, email, password = kwargs['email'], kwargs['email'], kwargs['password1']

在调用它们之后进行调试：

2010-07-09 19:24:35,020 DEBUG my@email.com
2010-07-09 19:24:35,020 DEBUG {'password1': u'a', 'email': u'my@email.com'}
2010-07-09 19:24:35,020 DEBUG <registration.backends.default.DefaultBackend object at 0x15c6090>
2010-07-09 19:24:35,021 DEBUG backend.register
2010-07-09 19:24:35,021 DEBUG {}

为什么数据会丢失呢？我是不是做错了什么？

@编辑给Silent-Ghost

 register() takes exactly 2 arguments (3 given)

 112.  backend = request.session['backend']
 113. logging.debug(backend)
 114. user = backend.register(request, userdata) 

Answer 1

这个完全可以工作

class Logging():
    def debug(self,f):
        print f
class DefaultBackend(object):
    def register(self, request, **kwargs):
        logging.debug("backend.register")
        logging.debug(kwargs)

        username, email, password = kwargs['email'], kwargs['email'], kwargs['password1']

class Request:
    def __init__(self):
        self.session = {}
request = Request()
logging=Logging()
request.session['temp_data']={'password1': u'a', 'email': u'my@email.com'}
request.session['backend']=DefaultBackend()



data = request.session['temp_data']
email = data['email']

logging.debug(email)

password1 = data['password1']
userdata = {'email': email, 'password1': password1}

logging.debug(userdata)

backend = request.session['backend']

logging.debug(backend)

user = backend.register(request,**userdata)

Answer 2

根据这个方法的定义：

1. 你需要把字典里的内容拆开
2. 你需要传入相关的 request 变量

大概是这样的：

backend.register(request, **userdata)

假设 register 是 backend 实例上的一个方法。

Answer 3

在register方法中，不需要去搞复杂的**。你只需要把字典直接传给register方法就可以了：

user = backend.register( request, userdata ) # you need to pass request as definition says

def register( self, request, userdata ): # note lack of **
    logging.debug("backend.register")
    logging.debug( userdata ) # should work as expected

    username, email, password = userdata['email'], userdata['email'], userdata['password1']