Flask - @login_required

To access an Index page, User should login first.

step1: __init__py

• set the login View page with ‘login’

#from flask import Flask
#from config import Config
#from flask_sqlalchemy import SQLAlchemy
#from flask_migrate import Migrate
from flask_login import LoginManager

#app = Flask(__name__)
#app.config.from_object(Config)
#db = SQLAlchemy(app)
#migrate = Migrate(app, db)
#login = LoginManager(app)
login.login_view = 'login' # for @login_required

#from myapp import routes, models

step2: put login_required on Routes/index

• under the @app.routes(/) and ``@app.routes(‘/’)
  
• put @login_required.
• So before sign-in, user automatically access to Log in page.
• without step1, step2 is not working

@app.route('/')
@app.route('/index')
@login_required
def index():

+ set Next page after login for better UX

• After user log in, redirect the page the user was supposed to visit
• It’s possible to use parameter of URL next
• for example: http://127.0.0.1:5000/login?next=%2Findex
  get index and redirect the page to index

from flask import render_template, flash, redirect, url_for, request
from werkzeug.urls import url_parse

#@app.route('/login', methods=['GET', 'POST'])
#def login():
#    if current_user.is_authenticated:
#        return redirect(url_for('index'))
#    form = LoginForm() # Get Login Form
#    if form.validate_on_submit():
#        user = User.query.filter_by(username=form.username.data).first() # get a user instance match with username#

#        if user is None or not user.check_password(form.password.data):  # is username is incorrect or password is wrong
#            flash('Invalid username or password') # show this message on the page
#            return redirect(url_for('login')) # and stay on login page
        login_user(user, remember=form.remember_me.data) # after user success to log in
        next_page = request.args.get('next') # user redirect to the page who is supposed to visit
        if not next_page or url_parse(next_page).netloc != '': # get parameter of URL
            next_page = url_for('index')
        return redirect(next_page)
    return render_template('login.html', title='Sign In', form=form)