Dynamically call function from another file in python while in runtime using flask-CodePudding

I would like to use flask to run some functions. Assume you have a file called myapp.py with a function run

def run():
    return 'special routed hello world'

and this main flask file, something like this

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'hello world'

@app.route('/<myapp>')
def open_app(myapp):
    from myapp import run
    return run()

So obvisouly that doesn't work, but how can I dynamically call these run functions when flask is already running. Is this even possible? In other words: when someone opens for example .../foobar, the function open_app with parameter foobar is begin called. In that function, from the file foobar.py (let's assume that file exists) import function run, run it and return the result from that function.

CodePudding user response：

In fact, it is possible to use importlib, especially import_modulein combination with getattr, to dynamically call up functions of a module. And I have security concerns too.

The following two examples show a kind of simple RPC implementation.

The first example uses a dictionary for modules. If a module with the name is available, the run function is called. It allows a strong restriction. Optimization is certainly possible and probably necessary.

The second example shows a possibility of calling different functions within different modules with parameters. In spite of everything, as with the previous version, all modules are in one package called "actions" to ensure that calls can be limited. I also think a variant with POST is more suitable for this purpose than using variable rules.

Remember these are strong simplifications. Protocols such as JSON-RPC will certainly help as a guide during implementation.

from flask import Flask
from flask import jsonify, request, jsonify
from importlib import import_module
from actions import *

app = Flask(__name__)
app.secret_key = 'your secret here'

@app.route('/exec/<string:action>', methods=['POST'])
def exec(action):
    result = cmddict[action].run()
    return jsonify(result=result)

@app.route('/call', methods=['POST'])
def call():
    data = request.get_json()
    module = data.get('module')
    method = data.get('method')
    params = data.get('params')

    try:
        # import module by name
        m = import_module(f'actions.{module}', __name__)
        # get function by name
        f = getattr(m, method)
        # call function with params
        result = f(**params) if isinstance(params, dict) else f(*params)
        return jsonify(result=result, error=None)
    except Exception as err:
        return jsonify(result=None, error=f'{err}')

# ./actions/__init__py
__all__ = ['demo']

from importlib import import_module

cmddict = {}
for _ in __all__:
    cmddict[_] = import_module(f'actions.{_}', __name__)
__all__.append('cmddict')

# ./actions/demo.py
def run():
    return f'hello world'

def func(*args, **kwargs):
    print('func', args, kwargs)
``