Question

以下是我想要组合的两个装饰器，因为它们非常相似，不同之处在于如何处理未经过身份验证的用户。我更愿意拥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

目前我正在将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():
    ...

我使用Bottle框架在python 3.3上。有可能做我想要的吗？怎么样？

Answer 1

只需添加另一个包装器即可捕获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

我已将您的原始requireAuthentication功能重命名为decorator（因为这是该功能所做的，它修饰了fn）并将旧decorator重命名为{{ 1}}，通常的惯例。

无论你在后放置，wrapper是一个表达式，首先进行评估以找到实际的装饰器函数。 @表示您要调用@helpers.requireAuthentication()，然后将返回值用作requireAuthentication行适用的函数的实际装饰器。

Answer 2

您可以为这两个装饰器创建包装器：

def requireAuthentication(json=False):
    if json:
        return helpers.requireAuthenticationJSON
    else:
        return helpers.requireAuthentication

或者

import functools
# Authentication decorator for routes
# Will redirect to the login page if not authenticated
def requireAuthentication(json=False):
    def requireAuthentication(fn):
        @functools.wraps(fn)
        def decorator(*args, **kwargs):
            # Is user logged on?
            if "user" in request.session:
                return fn(*args, **kwargs)
            if json:
                 return {
                "exception": "NotAuthorized",
                "error" : "You are not authorized, please log on"
            }
            return redirect('/login?url={0}{1}'.format(request.path, 
                                                       ("?" + request.query_string if request.query_string else '')))
        return decorator
    return requireAuthentication

将两个python装饰器合二为一

2 个答案: