How to print from Flask @app.route to python console

Question

I would like to simply print a "hello world" to the python console after /button is called by the user.

This is my naive approach:

@app.route('/button/') def button_clicked():     print 'Hello world!'     return redirect('/') 

Background: I would like to execute other python commands from flask (not shell). "print" should be the easiest case. I believe I have not understood a basic twist here. Thanks in advance!

Answer 1

An easy way to do this is by printing to stderr. You can do that like this:

from __future__ import print_function # In python 2.7 import sys  @app.route('/button/') def button_clicked():     print('Hello world!', file=sys.stderr)     return redirect('/') 

Flask will display things printed to stderr in the console. For other ways of printing to stderr, see this stackoverflow post

Answer 2

We can also use logging to print data on the console.

Example:

import logging from flask import Flask  app = Flask(__name__)  @app.route('/print') def printMsg():     app.logger.warning('testing warning log')     app.logger.error('testing error log')     app.logger.info('testing info log')     return "Check your console"  if __name__ == '__main__':     app.run(debug=True)