将函数传递给 cherrypy 中的装饰器

Question

如何将 index() 传递给名为 uppercase() 的装饰函数。我希望从 index() 传递的值被大写。

我收到这个错误：

500 Internal Server Error
The server encountered an unexpected condition which prevented it from fulfilling the request.

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.6/site-packages/cherrypy/_cprequest.py", line 638, in respond
    self._do_respond(path_info)
  File "/home/user/.local/lib/python3.6/site-packages/cherrypy/_cprequest.py", line 701, in _do_respond
    self.hooks.run('before_finalize')
  File "/home/user/.local/lib/python3.6/site-packages/cherrypy/_cprequest.py", line 95, in run
    self.run_hooks(iter(sorted(self[point])))
  File "/home/user/.local/lib/python3.6/site-packages/cherrypy/_cprequest.py", line 117, in run_hooks
    hook()
  File "/home/user/.local/lib/python3.6/site-packages/cherrypy/_cprequest.py", line 65, in __call__
    return self.callback(**self.kwargs)
TypeError: uppercase() missing 1 required positional argument: 'func'

import cherrypy
from cherrypy import tools

@cherrypy.tools.register('before_finalize')
def uppercase(func):
    def wrapper():
        original_result = func()
        modified_result = original_result.upper()
        return modified_result
    return wrapper

class HelloWorld(object):
    @cherrypy.expose
    @cherrypy.tools.uppercase()
    def index(self):
        return 'Hello!'


if __name__ == '__main__':
    cherrypy.tools.uppercase = cherrypy.Tool('before_finalize', uppercase)
    cherrypy.quickstart(HelloWorld())

Answer 1

你应该像这样使用装饰器：

@cherrypy.tools.uppercase
def index(self):
    return 'Hello!'

请注意 uppercase 之后缺少 () - 装饰器隐式采用第一个参数（装饰函数）并且不需要括号。

编辑：

根据the documentation，可以使用cherrypy.tools.register装饰器或cherrypy.Tool构造器来定义工具。在您的代码中，您定义了两次 uppercase 工具。

但是，在您的情况下，uppercase 装饰器不需要定义为 Tool，因为它不是每次都需要运行作为钩子的东西（ before_finalize).

因此，将它用作普通 Python 装饰器会更好，如下所示：

from functools import wraps

# just a plain Python decorator
def uppercase(func):
    @wraps(func) #preserve function attributes, such as its name
    def wrapper(*args):
        original_result = func(*args)
        modified_result = original_result.upper()
        return modified_result
    return wrapper

class HelloWorld(object):
    @cherrypy.expose
    @uppercase # decorated once, the exposed function is now uppercase(index) 
    def index(self):
        return 'Hello!'

将函数传递给 cherrypy 中的装饰器

passing function to a decorator in cherrypy

python

cherrypy