#coding=utf-8

 from flask import Flask

 from flask_sqlalchemy import SQLAlchemy

 from flask_migrate import Migrate,MigrateCommand

 from flask_script import Shell,Manager

 app = Flask(__name__)

 manager = Manager(app)

 app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://root:mysql@127.0.0.1:3306/Flask_test'

 app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = True

 app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = True

 db = SQLAlchemy(app)

 #第一个参数是Flask的实例，第二个参数是Sqlalchemy数据库实例

 migrate = Migrate(app,db) 

 #manager是Flask-Script的实例，这条语句在flask-Script中添加一个db命令

 manager.add_command('db',MigrateCommand)

 #定义模型Role

 class Role(db.Model):

     # 定义表名

     __tablename__ = 'roles'

     # 定义列对象

     id = db.Column(db.Integer, primary_key=True)

     name = db.Column(db.String(64), unique=True)

     user = db.relationship('User', backref='role')

     #repr()方法显示一个可读字符串，

     def __repr__(self):

         return 'Role:'.format(self.name)

 #定义用户

 class User(db.Model):

     __talbe__ = 'users'

     id = db.Column(db.Integer, primary_key=True)

     username = db.Column(db.String(64), unique=True, index=True)

     #设置外键

     role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))

     def __repr__(self):

         return 'User:'.format(self.username)

 if __name__ == '__main__':

     manager.run()