Flask-SQLAlchemy

　　Flask-SQLAlchemy主要是把Flask和SQLAlchemy進行無縫對接

settings.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-

class BaseConfig(object):
    # SESSION_TYPE = 'redis'  # session類型爲redis
    # SESSION_KEY_PREFIX = 'session:'  # 保存到session中的值的前綴
    # SESSION_PERMANENT = True  # 若是設置爲False，則關閉瀏覽器session就失效。
    # SESSION_USE_SIGNER = False  # 是否對發送到瀏覽器上 session:cookie值進行加密

    SQLALCHEMY_DATABASE_URI = "mysql+pymysql://root@127.0.0.1:3306/s7day145_2?charset=utf8"
    SQLALCHEMY_POOL_SIZE = 5
    SQLALCHEMY_POOL_TIMEOUT = 30
    SQLALCHEMY_POOL_RECYCLE = -1

    # 追蹤對象的修改而且發送信號
    SQLALCHEMY_TRACK_MODIFICATIONS = False


class ProductionConfig(BaseConfig):
    pass


class DevelopmentConfig(BaseConfig):
    pass


class TestingConfig(BaseConfig):
    pass

 run.py

from sansa import create_app

app = create_app()

if __name__ == '__main__':
    app.run()

 sansa __init__.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
db = SQLAlchemy()

from .models import *
from .views import account

def create_app():
    app = Flask(__name__)
    app.config.from_object('settings.DevelopmentConfig')

    # 將db註冊到app中
    db.init_app(app)

    # 註冊藍圖
    app.register_blueprint(account.account)
    return app

 views account.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-

from flask import Blueprint
from .. import db
from .. import models

account = Blueprint('account', __name__)


@account.route('/login')
def login():
    # 添加示例
    """
    db.session.add(models.Users(username='alex', pwd='123', gender=1))
    db.session.commit()

    obj = db.session.query(models.Users).filter(models.Users.id == 1).first()
    print(obj)

    PS: db.session和db.create_session
    """
    # db.session.add(models.Users(username='wupeiqi1', email='wupeiqi1@xx.com'))
    # db.session.commit()
    # db.session.close()
    #
    # db.session.add(models.Users(username='wupeiqi2', email='wupeiqi2@xx.com'))
    # db.session.commit()
    # db.session.close()
    # db.session.add(models.Users(username='alex1',email='alex1@live.com'))
    # db.session.commit()
    # db.session.close()



    user_list = db.session.query(models.Users).all()
    db.session.close()
    for item in user_list:
        print(item.username)


    return 'login'

 　　在上面代碼中db.init_app(app)主要是將db註冊到app中，在init_app函數源碼中，能看去讀取配置文件數據庫相關的配置

　　那在建立表和操做表都要鏈接數據庫，首先看建立表，以前SQLAlchemy定義表須要繼承一個基類Base = declarative_base(),而在Flask-SQLAlchemy只要繼承db.Model，而後其餘的和SQLAlchemy是同樣的

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from . import db
from flask import Flask,request


class Users(db.Model):
    """
    用戶表
    """
    __tablename__ = 'users'
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)

    def __repr__(self):
        return '<User %r>' % self.username

 　　在Flask-SQLAlchemy導入的SQLAlchemy進行實例化時，self.Model長這樣

        self.Model = self.make_declarative_base(model_class, metadata)

 　　而在make_declarative_base函數，會看到下列這段代碼，本質上是和SQLAlchemy同樣的

        if not isinstance(model, DeclarativeMeta):
            model = declarative_base(
                cls=model,
                name='Model',
                metadata=metadata,
                metaclass=DefaultMeta
            )

 

　　另外建立有一個函數db.create_all的函數，若是是離線腳本進行建立，則須要用到Flask的上下文

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from sansa import create_app
from sansa import db

app = create_app()

with app.app_context():
    db.create_all()

 　　上面建立表過程當中，還須要注意的是 在create_app裏，你要把定義好的表加載進來（也就是導入進來，原理和導入藍圖是同樣的），而且導入要在實例化db後，由於model裏要用到db

 

　　而操做表，什麼engine和拿鏈接都不用你作了，直接db.session進行操做就能夠了

    """
    db.session.add(models.Users(username='alex', pwd='123', gender=1))
    db.session.commit()

    obj = db.session.query(models.Users).filter(models.Users.id == 1).first()
    print(obj)

    PS: db.session和db.create_session
    """
    # db.session.add(models.Users(username='wupeiqi1', email='wupeiqi1@xx.com'))
    # db.session.commit()
    # db.session.close()
    #
    # db.session.add(models.Users(username='wupeiqi2', email='wupeiqi2@xx.com'))
    # db.session.commit()
    # db.session.close()
    # db.session.add(models.Users(username='alex1',email='alex1@live.com'))
    # db.session.commit()
    # db.session.close()



    user_list = db.session.query(models.Users).all()
    db.session.close()
    for item in user_list:
        print(item.username)

 

　　Flask-SQLAlchemy主要作了這幾件事

• 讀取配置
• 建立ORM基類
• 包含create_all
• engine
• 建立鏈接