将两个python装饰器合二为一

这里有两个我想要组合的装饰器,因为它们非常相似,区别在于如何处理未经过身份验证的用户.我更喜欢有一个可以用参数调用的装饰器.

# Authentication decorator for routes
# Will redirect to the login page if not authenticated
def requireAuthentication(fn):
    def decorator(**kwargs):
        # Is user logged on?
        if "user" in request.session:
            return fn(**kwargs)
        # No, redirect to login page
        else:
            redirect('/login?url={0}{1}'.format(request.path, ("?" + request.query_string if request.query_string else '')))
    return decorator

# Authentication decorator for routes
# Will return an error message (in JSON) if not authenticated
def requireAuthenticationJSON(fn):
    def decorator(**kwargs):
        # Is user logged on?
        if "user" in request.session:
            return fn(**kwargs)
        # No, return error
        else:
            return {
                "exception": "NotAuthorized",
                "error" : "You are not authorized, please log on"
            }
    return decorator

目前我正在使用这些装饰器用于特定路线,例如

@get('/day/')
@helpers.requireAuthentication
def day():
    ...

@get('/night/')
@helpers.requireAuthenticationJSON
def night():
    ...

我更喜欢这个:

@get('/day/')
@helpers.requireAuthentication()
def day():
    ...

@get('/night/')
@helpers.requireAuthentication(json = True)
def night():
    ...

我在使用Bottle框架的python 3.3上.有可能做我想要的吗?怎么样?

最佳答案
只需添加另一个包装器来捕获json参数:

def requireAuthentication(json=False):
    def decorator(fn):
        def wrapper(**kwargs):
            # Is user logged on?
            if "user" in request.session:
                return fn(**kwargs)

            # No, return error
            if json:
                return {
                    "exception": "NotAuthorized",
                    "error" : "You are not authorized, please log on"
                }
            redirect('/login?url={0}{1}'.format(request.path, ("?" + request.query_string if request.query_string else '')))
        return wrapper
    return decorator

我已经将你原来的requireAuthentication函数重命名为decorator(因为这就是那个函数所做的,它装饰了fn)并将旧的装饰器重命名为包装器,这是通常的约定.

无论你在@之后放置什么表达式,首先要评估实际的装饰器功能. @helpers.requireAuthentication()表示你想调用requireAuthentication,然后它的返回值被用作@ line适用的函数的实际装饰器.

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