Flask not executing function when wrapped in a decorator-CodePudding

I have an api based on flask. I am using also the multiprocessing module which may be involved in the following issue.

When using a non trivial wrapper the flask app just does not execute the wrapped task. There is also no error message und an no way to step into the task at hand with the pycharm debugger. The minimum example for such a decorator is the following

def test(task):
    def g(*args,**kwargs):
        return task(*args,**kwargs)
    return g

but this works:

def test(task):
        return task

Any Idea what is going on? The task is executed in a multiprocessing Pool

the task is executed in the following manner:

pool = multiprocessing.Pool(10, maxtasksperchild=10)
@app.route('/', methods=['POST'])
def test():
    task = other_script.task
    for i in range(3):
        pool.apply_async(task,args=(i,))

and in this other script we have something like:

@test
def task(arg):
    return 2

It would be really verbose to go into all the details how the api exactly works. so please feel free to share an educated guess based on this limited information

CodePudding user response：

A decorator is a function that wraps and replaces another function. Since the original function is replaced, you need to remember to copy the original function’s information to the new function. Use functools.wraps() to handle this for you.

Source

So try this way:

from flask import Flask, Response 
from functools import wraps

app = Flask(__name__)
app.config['TESTING'] = True

def token_required(f):
    @wraps(f)
    def decorated_function(*args, **kwargs):
        kwargs['hello'] = 'world!'
        return f( *args, **kwargs)
    return decorated_function

@app.route("/",methods=["GET"])
@token_required
def index(*args, **kwargs):
    return kwargs['hello']

if __name__ == '__main__':
    
    app.run(port=5000,debug=True)