25. Flask 数据库迁移 flask-migrate

pip3 install flask-migrate

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
import pymysql
pymysql.install_as_MySQLdb()
from flask_migrate import Migrate,MigrateCommand
from flask_script import Shell,Manager

app = Flask(__name__)
manager = Manager(app)

class Config(object):
    """配置参数"""
    # 设置连接数据库的URL
    user = 'root'
    password = '*****************'
    database = 'flask_ex'
    app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://%s:%s@127.0.0.1:3306/%s' % (user,password,database)

    # 设置sqlalchemy自动更跟踪数据库
    SQLALCHEMY_TRACK_MODIFICATIONS = True

    # 查询时会显示原始SQL语句
    # app.config['SQLALCHEMY_ECHO'] = True

    # 禁止自动提交数据处理
    app.config['SQLALCHEMY_COMMIT_ON_TEARDOWN'] = False

    # 设置密钥，用于csrf_token的加解密
    app.config["SECRET_KEY"] = "xhosd6f982yfhowefy29f"

# 读取配置
app.config.from_object(Config)

# 创建数据库sqlalchemy工具对象
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)

#定义模型类-作者
class Author(db.Model):
    __tablename__ = 'author'
    id = db.Column(db.Integer,primary_key=True)
    name = db.Column(db.String(32),unique=True)
    email = db.Column(db.String(64))
    au_book = db.relationship('Book',backref='author')
    def __str__(self):
        return 'Author:%s' %self.name


#定义模型类-书名
class Book(db.Model):
    __tablename__ = 'books'
    id = db.Column(db.Integer,primary_key=True)
    info = db.Column(db.String(32),unique=True)
    leader = db.Column(db.String(32))
    au_book = db.Column(db.Integer,db.ForeignKey('author.id'))
    def __str__(self):
        return 'Book:%s,%s'%(self.info,self.leader)


if __name__ == '__main__':

    # 通过管理对象来启动flask
    manager.run()

#这个命令会创建migrations文件夹，所有迁移文件都放在里面。
python3 db_database.py db init

#创建自动迁移脚本
python3 db_database.py db migrate -m "initial migration"

python3 db_database.py db upgrade

python3 db_database.py db downgrade 版本号