Python轻量级框架Flask开发web应用

from flask import Flask, render_template, request, redirect, url_for, session
from flask_sqlalchemy import SQLAlchemy
import config
 
app = Flask(__name__)
app.config.from_object(config)
db = SQLAlchemy(app)
 
class User(db.Model):
    __tablename__ = 'user'
    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
    username = db.Column(db.String(20), nullable=False)
    password = db.Column(db.String(20), nullable=False)
 
    def __str__(self):
        return 'User: {self.username}'.format(self=self)
 
@app.route('/')
def index():
    return render_template('index.html')
 
@app.route('/login/', methods=['GET', 'POST'])
def login():
    if request.method == 'GET':
        return render_template('login.html')
    else:
        username = request.form.get('username')
        password = request.form.get('password')
        user = User.query.filter(User.username == username, User.password == password).first()
        if user:
            session['username'] = username
            return redirect(url_for('index'))
        else:
            return 'Login failed.'
 
@app.route('/register/', methods=['GET', 'POST'])
def register():
    if request.method == 'GET':
        return render_template('register.html')
    else:
        username = request.form.get('username')
        password = request.form.get('password')
        user = User(username=username, password=password)
        db.session.add(user)
        db.session.commit()
        return redirect(url_for('login'))
 
@app.route('/logout/')
def logout():
    session.clear()
    return redirect(url_for('index'))
 
if __name__ == '__main__':
    app.run(debug=True)

这段代码是一个简单的用户登录注册系统的Flask应用示例。它展示了如何使用Flask框架结合SQLAlchemy来创建数据库模型，处理简单的登录和注册逻辑，并使用session来管理用户会话。这个示例提供了一个很好的起点，对于想要学习Flask web开发的开发者来说非常有帮助。