flask-sqlalchemy的使用

1.安装

pip3 isntall flask-sqlalchemy

2.实例化一个sqlalchemy对象

# __init__.py

from flask import Flask
from flask_session import Session

from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()


# 因为是初始化数据库，所以操作要放在__init__.py文件中。
# manager.py文件中只需要执行app.run()启动flask即可。

3.初始化数据库表

# models.py文件

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column
from sqlalchemy import Integer,String,Text,Date,DateTime
from sqlalchemy import create_engine
from day122 import db    # 倒入刚才生成的sqlalchemy对象


class Users(db.Model):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String(32), index=True, nullable=False)
    # depart_id = Column(Integer)


# __init__.py
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()

from .models import *

def create_app():

    app = Flask(__name__)
    app.config.from_object('settings.ProdConfig')

    app.register_blueprint(ac)
    app.register_blueprint(user)

    # Session(app)

    db.init_app(app)

    return app

# 这里from .models import *操作必须放在实例化sqlalchemy之后，因为该操作倒入的db模块里面使用了sqlalchemy对象。

4.手动创建数据库表

from mywork import db,create_app

app = create_app()
app_ctx = app.app_context() # app_ctx = app/g
with app_ctx: # __enter__,通过LocalStack放入Local中
    db.create_all() # 调用LocalStack放入Local中获取app，再去app中获取配置

5.使用数据库

from mywork import db
from mywork import models

@ac.route('/login')
def login():
    ret = db.session.query(models.Users).all()
    for row in ret:
        print(row.id,row.name)

    return 'Login'

6.数据库表的迁移

依赖：flask-script

pip3 install flask-migrate

from flask_migrate import Migrate, MigrateCommand

Migrate(app, db)

"""
# 数据库迁移命名
    python manage.py db init
    python manage.py db migrate
    python manage.py db upgrade
"""
manager.add_command('db', MigrateCommand)