搭建 Flask Web 应用编程环境

import os

from dotenv import load_dotenv
from flask import Flask, jsonify, request
from flask_login import (LoginManager, UserMixin, current_user, 
    login_required, login_user, logout_user)
from flask_migrate import Migrate
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy.exc import SQLAlchemyError
from werkzeug.security import check_password_hash, generate_password_hash

load_dotenv()

db = SQLAlchemy()
login_manager = LoginManager()
migrate = Migrate()


class User(UserMixin, db.Model):
    __tablename__ = 'users'

    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(64), unique=True, nullable=False, index=True)
    password_hash = db.Column(db.String(255), nullable=False)

    def set_password(self, raw):
        ''' 保存密码哈希 '''
        self.password_hash = generate_password_hash(raw)

    def check_password(self, raw):
        return check_password_hash(self.password_hash, raw)


def create_app():
    app = Flask(__name__)
    app.config['SECRET_KEY'] = os.getenv('SECRET_KEY', 'dev-secret-change-me')
    app.config['SQLALCHEMY_DATABASE_URI'] = os.getenv('DATABASE_URL', 'sqlite:///app.db')

    db.init_app(app)
    migrate.init_app(app, db)
    login_manager.init_app(app)

    @login_manager.user_loader
    def load_user(user_id):
        return db.session.get(User, int(user_id))

    @login_manager.unauthorized_handler
    def unauthorized():
        return jsonify({'error': '未登录'}), 401

    @app.get('/')
    def index():
        state = {
            'status': 'ok',
            'user': current_user.username if current_user.is_authenticated else None,
        }
        try:
            state['users'] = db.session.query(User).count()
        except SQLAlchemyError:
            db.session.rollback()
            state['users'] = None
            state['hint'] = '数据表还没建，先执行 flask --app app db upgrade'
        return jsonify(state)

    @app.post('/register')
    def register():
        data = request.get_json(silent=True) or {}
        username = str(data.get('username') or '').strip()
        password = str(data.get('password') or '')
        if not username or not password:
            return jsonify({'error': '需要 username 和 password 两个字段'}), 400
        if db.session.query(User).filter_by(username=username).first():
            return jsonify({'error': '用户名已存在'}), 409

        user = User(username=username)
        user.set_password(password)
        db.session.add(user)
        db.session.commit()
        return jsonify({'id': user.id, 'username': user.username}), 201

    @app.post('/login')
    def login():
        data = request.get_json(silent=True) or {}
        username = str(data.get('username') or '').strip()
        password = str(data.get('password') or '')
        user = db.session.query(User).filter_by(username=username).first()
        if user is None or not user.check_password(password):
            return jsonify({'error': '用户名或密码不正确'}), 401
        login_user(user)
        return jsonify({'id': user.id, 'username': user.username})

    @app.post('/logout')
    @login_required
    def logout():
        logout_user()
        return jsonify({'status': '已登出'})

    @app.get('/profile')
    @login_required
    def profile():
        return jsonify({'id': current_user.id, 'username': current_user.username})

    return app


app = create_app()


if __name__ == '__main__':
    print('数据库  : {}'.format(app.config['SQLALCHEMY_DATABASE_URI']))
    app.run(port=5000, debug=True)
    # 生产环境服务器
    #from waitress import serve
    #serve(app, host='0.0.0.0', port=8080, threads=4)