How Flask session variables work

dict_example.py

# python 3 
# a review of Python’s dictionary format

# create a new dict - named session - with three key:value pairs:
session = { 'logged_in': True, 'user': 'Harry Potter', 'password': 'parseltongue' }

# create a new dict - named session2 - with three key:value pairs
# another way to create a dict)
session2 = {}
session2['logged_in'] = False
session2['user'] = 'Hermione Granger'
session2['password'] = 'muggle-born'

# access a value by dict name and key 
print( session['user'] )

print( session2['user'] )

quick_session.py

# adapted from Head First Python, 2nd edition, by Paul Barry - chapter 10
# this is how a session variable allows you to pass values between pages 

from flask import Flask, session

app = Flask(__name__)

app.secret_key = 'You Will Never Guess'


@app.route('/setuser/<user>')
def setuser(user):
    session['user'] = user
    return 'User value set to: ' + session['user']


@app.route('/getuser')
def getuser():
    return 'User value was previously set to: ' + session['user']


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

quick_session_NOT.py

# compare to quick_session.py - below in this gist - this version does NOT use session
# Therefore, it cannot pass variables to another route 

from flask import Flask

app = Flask(__name__)


@app.route('/setuser/<user>')
def setuser(user):
    new_user = user
    return 'User value set to: ' + new_user


@app.route('/getuser')
def getuser():
    return 'User value was previously set to: ' + new_user


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