问题描述
@api.route('/api/get_contacts')
def get_contacts():
with pymongo.MongoClient(f"mongodb+srv://{mongo_username}:{mongo_password}@dev.glstt.mongodb.net/xxxx?retryWrites=true&w=majority") as document:
这个看的太多了。我正在努力使其成为:
@api.route('/api/get_contacts')
@mongo
def get_contacts():
问题是,我不太了解装饰器。 所以,这就是我到目前为止所做的:
def mongo(f):
@wraps(f)
def wrap (*args,**kwargs):
with pymongo.MongoClient(f"mongodb+srv://{mongo_username}:{mongo_password}@dev.glstt.mongodb.net/xxx?retryWrites=true&w=majority") as document:
return f(document)
return wrap
不确定我需要做什么才能让装饰器在代码前面加上“with 运算符”,然后传递 x,然后将文档返回给路由函数。
解决方法
装饰器的工作原理是用 decorator(function)
替换你的函数。例如:
@decorator
def my_function():
pass
等于
def my_function():
pass
my_function = decorator(my_function)
这意味着你可以从装饰器返回一个可调用的函数,每次你用参数调用它时,它都会用特定的参数调用被装饰的函数。
例如:
import functools
def decorator(decorated_function):
@functools.wraps(decorated_function) # This means that the function that returns from this decorator,"wrapper",will keep the decorated_function's name,`__doc__` argument and more.
def wrapper(*args,**kwargs):
"""
Every time you will call the function that returned from the decorator,this function will be called with the particular arguments in args and kwargs.
"""
return decorated_function(*args,**kwargs) + 10
return wrapper
@decorator
def func(n):
return n * 2
result = func(2) # here we called the function `wrapper`,the result is func(2) + 10,as we did when we called the function.
print(result) # 14
我们也可以print(func)
,结果类似于
<function func at 0x7f5eb16b0040>
,如果我们没有使用 functools.wraps
:<function decorator.<locals>.wrapper at 0x7fba9ba0f040>
。
现在你的问题, 当你堆叠装饰器时,
@c
@b
@a
def func(): pass
订单是
c(b(a(func)))
因此,名为 mongo
的函数应该从 api.route('/api/get_contacts')
获取参数“request”。 (我不知道这是什么框架,所以我无法预测这个框架是否将请求作为函数参数提供)。
如果框架没有将请求作为参数传递:
def mongo(f):
@functools.wraps(f)
def wrap():
with pymongo.MongoClient(f"mongodb+srv://{mongo_username}:{mongo_password}@dev.glstt.mongodb.net/xxx?retryWrites=true&w=majority") as document:
return f(document)
return wrap
如果有:
def mongo(f):
@functools.wraps(f)
def wrap(request):
# do something with the request
with pymongo.MongoClient(f"mongodb+srv://{mongo_username}:{mongo_password}@dev.glstt.mongodb.net/xxx?retryWrites=true&w=majority") as document:
return f(document)
return wrap
然后它允许你这样做:
@api.route('/api/get_contacts')
@mongo
def get_contacts(document):
pass