flask - sqlalchemy

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a. 下載安裝
    pip3 install flask-sqlalchemy
b. chun.__init__.py 
    導入並實例化SQLAlchemy
    from flask_sqlalchemy import SQLAlchemy
    db = SQLAlchemy()
    
    注意事項：
         - 必須在導入藍圖以前
         - 必須導入models.py 
c. 初始化
    db.init_app(app)
    
d. 在配置文件中寫入配置
    # ##### SQLALchemy配置文件 #####
    SQLALCHEMY_DATABASE_URI = "mysql+pymysql://root:123456@127.0.0.1:3306/s9day122?charset=utf8"
    SQLALCHEMY_POOL_SIZE = 10
    SQLALCHEMY_MAX_OVERFLOW = 5

e. 建立models.py中的類（對應數據庫表）
    chun/models.py 
        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 chun import db


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

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

f. 生成表（使用app上下文）
    from chun import db,create_app

    app = create_app()
    app_ctx = app.app_context() # app_ctx = app/g
    with app_ctx: # __enter__,經過LocalStack放入Local中
        db.create_all() # 調用LocalStack放入Local中獲取app，再去app中獲取配置

        
g. 基於ORM對數據庫進行操做。
    from flask import Blueprint
    from chun import db
    from chun import models
    us = Blueprint('us',__name__)


    @us.route('/index')
    def index():
        # 使用SQLAlchemy在數據庫中插入一條數據
        # db.session.add(models.Users(name='高件套',depart_id=1))
        # db.session.commit()
        # db.session.remove()
        result = db.session.query(models.Users).all()
        print(result)
        db.session.remove()

        return 'Index'