Added Flask Authentication System - fixed #236

scripts/Authentication System using Flask/main.py

@@ -0,0 +1,95 @@
+from flask import Flask, render_template, redirect, url_for, flash
+from flask_sqlalchemy import SQLAlchemy
+from flask_login import UserMixin, LoginManager, login_user, login_required, current_user, logout_user
+from flask_wtf import FlaskForm
+from wtforms import StringField, PasswordField, SubmitField
+from wtforms.validators import ValidationError, InputRequired, Length
+from flask_bcrypt import Bcrypt
+
+app = Flask(__name__)
+app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///database.db'
+db = SQLAlchemy(app)
+app.config['SECRET_KEY'] = 'YOUR_SECRET_KEY'
+bcrypt = Bcrypt(app)
+
+login_manager = LoginManager()
+login_manager.init_app(app)
+login_manager.login_view = "login"
+
+@login_manager.user_loader
+def load_user(user_id):
+    return User.query.get(int(user_id))
+
+
+class User(db.Model, UserMixin):
+    id = db.Column(db.Integer, primary_key=True)
+    username = db.Column(db.String(20), nullable=False, unique=True)
+    password = db.Column(db.String(80), nullable=False)
+
+class RegistrationForm(FlaskForm):
+    username = StringField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "Username"})
+    password = PasswordField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "Password"})
+    submit = SubmitField("Register")
+
+    def validate_username(self, username):
+        existing_user_username = User.query.filter_by(username=username.data).first()
+        if existing_user_username:
+            raise ValidationError("That username already exists! Try a different one.")
+
+class LoginForm(FlaskForm):
+    username = StringField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "Username"})
+    password = PasswordField(validators=[InputRequired(), Length(min=4, max=20)], render_kw={"placeholder": "Password"})
+    submit = SubmitField("Login")
+
+@app.route('/')
+def home():
+    return render_template('home.html')
+
+@app.route('/dashboard', methods=["GET", "POST"])
+@login_required
+def dashboard():
+    return render_template('dashboard.html')
+
+@app.route('/logout', methods=["GET", "POST"])
+@login_required
+def logout():
+    logout_user()
+    return redirect(url_for('login'))
+
+@app.route('/login', methods=["GET", "POST"])
+def login():
+    if current_user.is_authenticated:
+        return redirect(url_for('dashboard'))
+
+    form = LoginForm()
+
+    if form.validate_on_submit():
+        user = User.query.filter_by(username=form.username.data).first()
+        if user:
+            if bcrypt.check_password_hash(user.password, form.password.data):
+                login_user(user)
+                return redirect(url_for('dashboard'))
+            else:
+                flash("Incorrect Password! Please Try again")
+        else:
+            flash("This email is not registered. Try Signing Up!")
+
+    return render_template('login.html', form=form)
+
+@app.route('/register', methods=["GET", "POST"])
+def register():
+    if current_user.is_authenticated:
+        return redirect(url_for('dashboard'))
+    form = RegistrationForm()
+
+    if form.validate_on_submit():
+        hashed_password = bcrypt.generate_password_hash(form.password.data)
+        new_user = User(username=form.username.data, password=hashed_password)
+        db.session.add(new_user)
+        db.session.commit()
+        return redirect(url_for('login'))
+
+    return render_template('register.html', form=form)
+
+if __name__ == '__main__':
+    app.run(debug=True)