CODEWITHSUNDEEP
flask
d4rty
d4rty

Reputation: 4178

How to start Flask and Flask-SocketIO via the command line flask run

I started with an application that has several webservices defined. I was able to start the application via flask run on the command line. Afterwards, I integrated flask-sckoetio (i.e. I added the lines from flask_socketio import SocketIO, emit and socketio = SocketIO(app)) and now I'm not able anymore to start the server via flask run.

from flask import Flask, request, abort
from flask_socketio import SocketIO, emit


app = Flask(__name__)
socketio = SocketIO(app)

@app.route('/do_sth', methods=['POST'])
def do_sth():
    return ""

I get the following message on the console:

 * Serving Flask-SocketIO app "webservices.py"
 * Forcing debug mode off
WebSocket transport not available. Install eventlet or gevent and gevent-websocket for improved perform
ance.
c:\program files\python36\lib\site-packages\flask_socketio\__init__.py:496: Warning: Silently ignoring
app.run() because the application is run from the flask command line executable.  Consider putting app.
run() behind an if __name__ == "__main__" guard to silence this warning.
  use_reloader=use_reloader, **kwargs)

So I updated my code to this:

from flask import Flask, request, abort
from flask_socketio import SocketIO, emit


app = Flask(__name__)
socketio = SocketIO(app)

@app.route('/do_sth', methods=['POST'])
def do_sth():
    return ""

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

But I still get the same error message and the server doesn't start. However, if I just execute the script everything works. But why is flask run not possible anymore?

Upvotes: 4

Views: 5250

Answers (2)

Andrey Topoleov
Andrey Topoleov

Reputation: 1909

It happens because of variable __name__ is equal to "__main__" only when the file called directly with a command like python file.py. But your file was imported and his __name__ variable is setted to name of a module which import them.

Solution:

Just delete string if __name__ == "__main__":

Upvotes: 1

Deep Diwani
Deep Diwani

Reputation: 11

Did you install eventlet or gevent, which are mentioned in the error message?

They are also listed under requirements in flask-socketIO documentation. Try installing them first.

After installing one of them, you can just use flask run to start your application.

Upvotes: 0

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