How can I run a python script from within Flask

Jack022 Published at Java

Jack022

I have a Flask script which creates a website and prints some data dynamically. - The data which it prints should come from another python script.

The current problem that I'm facing is that if I put the line that executes the python script before the line that executes the Flask app, it will run the Python script without running Flask; and vice versa.

Python script:

import websocket
from bitmex_websocket import Instrument
from bitmex_websocket.constants import InstrumentChannels
from bitmex_websocket.constants import Channels
import json

websocket.enableTrace(True)

sells = 0
buys = 0


channels = [
    InstrumentChannels.trade,
]


XBTUSD = Instrument(symbol='XBTUSD',
                    channels=channels)
XBTUSD.on('action', lambda msg: test(msg))


def test(msg):
    parsed = json.loads(json.dumps(msg))


    print(parsed)

XBTUSD.run_forever()

Flask script (NB: price should be the variable 'parsed' from the other script):

# Start with a basic flask app webpage.
from flask_socketio import SocketIO, emit
from flask import Flask, render_template, url_for, copy_current_request_context
from random import random
from time import sleep
from threading import Thread, Event
import requests, json
import time

__author__ = 'slynn'

app = Flask(__name__)
app.config['SECRET_KEY'] = 'secret!'
app.config['DEBUG'] = True

#turn the flask app into a socketio app
socketio = SocketIO(app)

#random number Generator Thread
thread = Thread()
thread_stop_event = Event()

class RandomThread(Thread):
    def __init__(self):
        self.delay = 1
        super(RandomThread, self).__init__()

    def randomNumberGenerator(self):
        while not thread_stop_event.isSet():
            socketio.emit('newnumber', {'number': parsed}, namespace='/test')
            sleep(self.delay)

    def run(self):
        self.randomNumberGenerator()


@app.route('/')
def index():
    #only by sending this page first will the client be connected to the socketio instance
    return render_template('index.html')

@socketio.on('connect', namespace='/test')
def test_connect():
    # need visibility of the global thread object
    global thread
    print('Client connected')

    #Start the random number generator thread only if the thread has not been started before.
    if not thread.isAlive():
        print("Starting Thread")
        thread = RandomThread()
        thread.start()

@socketio.on('disconnect', namespace='/test')
def test_disconnect():
    print('Client disconnected')


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

Julian Camilleri

Using import:

Wrap what the python script (e.g. website_generator.py) is generating into a function.
Place it in the same directory as your app.py or flask.py.
Use from website_generator import function_name in flask.py
Run it using function_name()

You can use other functions such as subprocess.call et cetera; although they might not give you the response.

Example using import:

from flask import Flask
import your_module # this will be your file name; minus the `.py`

app = Flask(__name__)

@app.route('/')
def dynamic_page():
    return your_module.your_function_in_the_module()

if __name__ == '__main__':
    app.run(host='0.0.0.0', port='8000', debug=True)

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