My @app.route decorator is not triggering its function

Question

I am new to python and flask and I am encountering a problem with Flask. I am trying to use a local HTTP POST (webhook) to call a function from another file, but when I do nothing happens.

from flask import Flask
from BotSpeak import main

app = Flask(__name__)

@app.route('/', methods=['POST'])
def respond():
    main('hello')

if __name__ == '__main__':
    app.run()

This is my very basic Flask app. As you can see it is trying to call the main function from this file (BotSpeak):

from json import dumps
from httplib2 import Http

def main(botmsg):
    url = 'PLACEHOLDER FOR GOOGLE CHAT WEBHOOK URL'
    bot_message = {
        'text' : botmsg}

    message_headers = {'Content-Type': 'application/json; charset=UTF-8'}

    http_obj = Http()

    response = http_obj.request(
        uri=url,
        method='post',
        headers=message_headers,
        body=dumps(bot_message),
    )

    print(response)

if __name__ == '__main__':
    main("TEST MESSAGE")

This is the code that shoots local HTTP POSTs to my flask app:

import json
import requests

webhook_url ='http://127.0.0.1:5000/'

data = {PLACE HOLDER FOR JSON DATA}

r = requests.post(webhook_url, data=json.dumps(data), headers={'Content-Type': 'application/json'})

I can call the main function from other files outside the flask app and it'll work but it just wont trigger in the app.route decorator like it should. I really appreciate anyone's help and I encourage you to throw these into VS Code and try it for yourself.

Answer 1

If you're using flask you don't have to manually construct an HTTP response using httplib2 unless you have some very specific use case.

In your case you can just return bot_message since if the return value of a Flask handler is a dict it will convert it to a JSON response (including the correct headers). See

https://flask.palletsprojects.com/en/2.0.x/quickstart/#about-responses

In other words, your entire route handler could be rewritten (based off your example at least):

@app.route('/', methods=['POST'])
def respond():
    return {'text': 'hello'}

If you want to pass the handling off to some utility function you can do that too, just make sure it returns a value, and that you in turn return an appropriate value from your respond() function.