本篇导航:
- 介绍
- 使用
- SQLAlchemy-Utils
一. 介绍
SQLAlchemy是一个基于Python实现的ORM框架。该框架建立在 DB API之上,使用关系对象映射进行数据库操作,简言之便是:将类和对象转换成SQL,然后使用数据API执行SQL并获取执行结果。
pip install sqlalchemy -i http://pypi.douban.com/simple --trusted-host pypi.douban.com
组成部分:
- Engine,框架的引擎
- Connection Pooling ,数据库连接池
- Dialect,选择连接数据库的DB API种类
- Schema/Types,架构和类型
- SQL Exprression Language,SQL表达式语言
SQLAlchemy本身无法操作数据库,其必须以来pymsql等第三方插件,Dialect用于和数据API进行交流,根据配置文件的不同调用不同的数据库API,从而实现对数据库的操作,如:
MySQL-Python mysql+mysqldb://<user>:<password>@<host>[:<port>]/<dbname> pymysql mysql+pymysql://<username>:<password>@<host>/<dbname>[?<options>] MySQL-Connector mysql+mysqlconnector://<user>:<password>@<host>[:<port>]/<dbname> cx_Oracle oracle+cx_oracle://user:pass@host:port/dbname[?key=value&key=value...] 更多:http://docs.sqlalchemy.org/en/latest/dialects/index.html
二. 使用
1、 执行原生SQL语句
import time import threading import sqlalchemy from sqlalchemy import create_engine from sqlalchemy.engine.base import Engine engine = create_engine( "mysql+pymysql://root:[email protected]:3306/t1?charset=utf8", max_overflow=0, # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30, # 池中没有线程最多等待的时间,否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收(重置) ) def task(arg): conn = engine.raw_connection() cursor = conn.cursor() cursor.execute( "select * from t1" ) result = cursor.fetchall() cursor.close() conn.close() for i in range(20): t = threading.Thread(target=task, args=(i,)) t.start()
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading import sqlalchemy from sqlalchemy import create_engine from sqlalchemy.engine.base import Engine engine = create_engine("mysql+pymysql://root:[email protected]:3306/t1", max_overflow=0, pool_size=5) def task(arg): conn = engine.contextual_connect() with conn: cur = conn.execute( "select * from t1" ) result = cur.fetchall() print(result) for i in range(20): t = threading.Thread(target=task, args=(i,)) t.start()
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading import sqlalchemy from sqlalchemy import create_engine from sqlalchemy.engine.base import Engine from sqlalchemy.engine.result import ResultProxy engine = create_engine("mysql+pymysql://root:[email protected]:3306/t1", max_overflow=0, pool_size=5) def task(arg): cur = engine.execute("select * from t1") result = cur.fetchall() cur.close() print(result) for i in range(20): t = threading.Thread(target=task, args=(i,)) t.start()
注意: 查看连接 show status like ‘Threads%‘;
2.、ORM
a.、创建数据库表
#!/usr/bin/env python # -*- coding:utf-8 -*- import datetime from sqlalchemy import create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, Text, ForeignKey, DateTime, UniqueConstraint, Index Base = declarative_base() class Users(Base): __tablename__ = ‘users‘ id = Column(Integer, primary_key=True) name = Column(String(32), index=True, nullable=False) # email = Column(String(32), unique=True) # ctime = Column(DateTime, default=datetime.datetime.now) # extra = Column(Text, nullable=True) __table_args__ = ( # UniqueConstraint(‘id‘, ‘name‘, name=‘uix_id_name‘), # Index(‘ix_id_name‘, ‘name‘, ‘email‘), ) def init_db(): """ 根据类创建数据库表 :return: """ engine = create_engine( "mysql+pymysql://root:[email protected]:3306/s6?charset=utf8", max_overflow=0, # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30, # 池中没有线程最多等待的时间,否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收(重置) ) Base.metadata.create_all(engine) def drop_db(): """ 根据类删除数据库表 :return: """ engine = create_engine( "mysql+pymysql://root:[email protected]:3306/s6?charset=utf8", max_overflow=0, # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30, # 池中没有线程最多等待的时间,否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收(重置) ) Base.metadata.drop_all(engine) if __name__ == ‘__main__‘: drop_db() init_db()
创建单表
#!/usr/bin/env python # -*- coding:utf-8 -*- import datetime from sqlalchemy import create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, Text, ForeignKey, DateTime, UniqueConstraint, Index from sqlalchemy.orm import relationship Base = declarative_base() # ##################### 单表示例 ######################### class Users(Base): __tablename__ = ‘users‘ id = Column(Integer, primary_key=True) name = Column(String(32), index=True) age = Column(Integer, default=18) email = Column(String(32), unique=True) ctime = Column(DateTime, default=datetime.datetime.now) extra = Column(Text, nullable=True) __table_args__ = ( # UniqueConstraint(‘id‘, ‘name‘, name=‘uix_id_name‘), # Index(‘ix_id_name‘, ‘name‘, ‘extra‘), ) class Hosts(Base): __tablename__ = ‘hosts‘ id = Column(Integer, primary_key=True) name = Column(String(32), index=True) ctime = Column(DateTime, default=datetime.datetime.now) # ##################### 一对多示例 ######################### class Hobby(Base): __tablename__ = ‘hobby‘ id = Column(Integer, primary_key=True) caption = Column(String(50), default=‘篮球‘) class Person(Base): __tablename__ = ‘person‘ nid = Column(Integer, primary_key=True) name = Column(String(32), index=True, nullable=True) hobby_id = Column(Integer, ForeignKey("hobby.id")) # 与生成表结构无关,仅用于查询方便 hobby = relationship("Hobby", backref=‘pers‘) # ##################### 多对多示例 ######################### class Server2Group(Base): __tablename__ = ‘server2group‘ id = Column(Integer, primary_key=True, autoincrement=True) server_id = Column(Integer, ForeignKey(‘server.id‘)) group_id = Column(Integer, ForeignKey(‘group.id‘)) class Group(Base): __tablename__ = ‘group‘ id = Column(Integer, primary_key=True) name = Column(String(64), unique=True, nullable=False) # 与生成表结构无关,仅用于查询方便 servers = relationship(‘Server‘, secondary=‘server2group‘, backref=‘groups‘) class Server(Base): __tablename__ = ‘server‘ id = Column(Integer, primary_key=True, autoincrement=True) hostname = Column(String(64), unique=True, nullable=False) def init_db(): """ 根据类创建数据库表 :return: """ engine = create_engine( "mysql+pymysql://root:[email protected]:3306/s6?charset=utf8", max_overflow=0, # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30, # 池中没有线程最多等待的时间,否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收(重置) ) Base.metadata.create_all(engine) def drop_db(): """ 根据类删除数据库表 :return: """ engine = create_engine( "mysql+pymysql://root:[email protected]:3306/s6?charset=utf8", max_overflow=0, # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30, # 池中没有线程最多等待的时间,否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收(重置) ) Base.metadata.drop_all(engine) if __name__ == ‘__main__‘: drop_db() init_db()
创建多个表并包含Fk、M2M关系
b.、操作数据库表
#!/usr/bin/env python # -*- coding:utf-8 -*- from sqlalchemy.orm import sessionmaker from sqlalchemy import create_engine from models import Users engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6", max_overflow=0, pool_size=5) ##############方式一######################## Session = sessionmaker(bind=engine) # 每次执行数据库操作时,都需要创建一个session session = Session() # ############# 执行ORM操作 ############# obj1 = Users(name="alex1") session.add(obj1) # 提交事务 session.commit() # 关闭session session.close() ######################方式二#################### # 方式二:支持线程安全,为每个线程创建一个session # - threading.Local # - 唯一标识 # ScopedSession对象 # self.registry(), 加括号 创建session # self.registry(), 加括号 创建session # self.registry(), 加括号 创建session from greenlet import getcurrent as get_ident Session = sessionmaker(bind=engine) session = scoped_session(Session,get_ident) # session.add # 操作 session.remove()
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine from db import Users engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6", max_overflow=0, pool_size=5) Session = sessionmaker(bind=engine) def task(arg): session = Session() obj1 = Users(name="alex1") session.add(obj1) session.commit() for i in range(10): t = threading.Thread(target=task, args=(i,)) t.start()
多线程执行示例
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine from sqlalchemy.sql import text from db import Users, Hosts engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6", max_overflow=0, pool_size=5) Session = sessionmaker(bind=engine) session = Session() # ################ 添加 ################ """ obj1 = Users(name="wupeiqi") session.add(obj1) session.add_all([ Users(name="wupeiqi"), Users(name="alex"), Hosts(name="c1.com"), ]) session.commit() """ # ################ 删除 ################ """ session.query(Users).filter(Users.id > 2).delete() session.commit() """ # ################ 修改 ################ """ session.query(Users).filter(Users.id > 0).update({"name" : "099"}) session.query(Users).filter(Users.id > 0).update({Users.name: Users.name + "099"}, synchronize_session=False) session.query(Users).filter(Users.id > 0).update({"age": Users.age + 1}, synchronize_session="evaluate") session.commit() """ # ################ 查询 ################ """ r1 = session.query(Users).all() r2 = session.query(Users.name.label(‘xx‘), Users.age).all() r3 = session.query(Users).filter(Users.name == "alex").all() r4 = session.query(Users).filter_by(name=‘alex‘).all() r5 = session.query(Users).filter_by(name=‘alex‘).first() r6 = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name=‘fred‘).order_by(Users.id).all() r7 = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name=‘ed‘).all() """ session.close()
基本增删改查示例
# 条件 ret = session.query(Users).filter_by(name=‘alex‘).all() ret = session.query(Users).filter(Users.id > 1, Users.name == ‘eric‘).all() ret = session.query(Users).filter(Users.id.between(1, 3), Users.name == ‘eric‘).all() ret = session.query(Users).filter(Users.id.in_([1,3,4])).all() ret = session.query(Users).filter(~Users.id.in_([1,3,4])).all() ret = session.query(Users).filter(Users.id.in_(session.query(Users.id).filter_by(name=‘eric‘))).all() from sqlalchemy import and_, or_ ret = session.query(Users).filter(and_(Users.id > 3, Users.name == ‘eric‘)).all() ret = session.query(Users).filter(or_(Users.id < 2, Users.name == ‘eric‘)).all() ret = session.query(Users).filter( or_( Users.id < 2, and_(Users.name == ‘eric‘, Users.id > 3), Users.extra != "" )).all() # 通配符 ret = session.query(Users).filter(Users.name.like(‘e%‘)).all() ret = session.query(Users).filter(~Users.name.like(‘e%‘)).all() # 限制 ret = session.query(Users)[1:2] # 排序 ret = session.query(Users).order_by(Users.name.desc()).all() ret = session.query(Users).order_by(Users.name.desc(), Users.id.asc()).all() # 分组 from sqlalchemy.sql import func ret = session.query(Users).group_by(Users.extra).all() ret = session.query( func.max(Users.id), func.sum(Users.id), func.min(Users.id)).group_by(Users.name).all() ret = session.query( func.max(Users.id), func.sum(Users.id), func.min(Users.id)).group_by(Users.name).having(func.min(Users.id) >2).all() # 连表 ret = session.query(Users, Favor).filter(Users.id == Favor.nid).all() ret = session.query(Person).join(Favor).all() ret = session.query(Person).join(Favor, isouter=True).all() # 组合 q1 = session.query(Users.name).filter(Users.id > 2) q2 = session.query(Favor.caption).filter(Favor.nid < 2) ret = q1.union(q2).all() q1 = session.query(Users.name).filter(Users.id > 2) q2 = session.query(Favor.caption).filter(Favor.nid < 2) ret = q1.union_all(q2).all()
常用操作
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine from sqlalchemy.sql import text from sqlalchemy.engine.result import ResultProxy from db import Users, Hosts engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6", max_overflow=0, pool_size=5) Session = sessionmaker(bind=engine) session = Session() # 查询 # cursor = session.execute(‘select * from users‘) # result = cursor.fetchall() # 添加 cursor = session.execute(‘insert into users(name) values(:value)‘,params={"value":‘wupeiqi‘}) session.commit() print(cursor.lastrowid) session.close()
原生SQL语句
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine from sqlalchemy.sql import text from sqlalchemy.engine.result import ResultProxy from db import Users, Hosts, Hobby, Person engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6?charset=utf8", max_overflow=0, pool_size=5) Session = sessionmaker(bind=engine) session = Session() # 添加 """ session.add_all([ Hobby(caption=‘乒乓球‘), Hobby(caption=‘羽毛球‘), Person(name=‘张三‘, hobby_id=3), Person(name=‘李四‘, hobby_id=4), ]) person = Person(name=‘张九‘, hobby=Hobby(caption=‘姑娘‘)) session.add(person) hb = Hobby(caption=‘人妖‘) hb.pers = [Person(name=‘文飞‘), Person(name=‘博雅‘)] session.add(hb) session.commit() """ # 使用relationship正向查询 """ v = session.query(Person).first() print(v.name) print(v.hobby.caption) """ # 使用relationship反向查询 """ v = session.query(Hobby).first() print(v.caption) print(v.pers) """ session.close()
基于relationship操作ForeignKey
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine from sqlalchemy.sql import text from sqlalchemy.engine.result import ResultProxy from db import Users, Hosts, Hobby, Person, Group, Server, Server2Group engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6?charset=utf8", max_overflow=0, pool_size=5) Session = sessionmaker(bind=engine) session = Session() # 添加 """ session.add_all([ Server(hostname=‘c1.com‘), Server(hostname=‘c2.com‘), Group(name=‘A组‘), Group(name=‘B组‘), ]) session.commit() s2g = Server2Group(server_id=1, group_id=1) session.add(s2g) session.commit() gp = Group(name=‘C组‘) gp.servers = [Server(hostname=‘c3.com‘),Server(hostname=‘c4.com‘)] session.add(gp) session.commit() ser = Server(hostname=‘c6.com‘) ser.groups = [Group(name=‘F组‘),Group(name=‘G组‘)] session.add(ser) session.commit() """ # 使用relationship正向查询 """ v = session.query(Group).first() print(v.name) print(v.servers) """ # 使用relationship反向查询 """ v = session.query(Server).first() print(v.hostname) print(v.groups) """ session.close()
基于relationship操作m2m
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine from sqlalchemy.sql import text, func from sqlalchemy.engine.result import ResultProxy from db import Users, Hosts, Hobby, Person, Group, Server, Server2Group engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6?charset=utf8", max_overflow=0, pool_size=5) Session = sessionmaker(bind=engine) session = Session() # 关联子查询 subqry = session.query(func.count(Server.id).label("sid")).filter(Server.id == Group.id).correlate(Group).as_scalar() result = session.query(Group.name, subqry) """ SELECT `group`.name AS group_name, (SELECT count(server.id) AS sid FROM server WHERE server.id = `group`.id) AS anon_1 FROM `group` """ # 原生SQL """ # 查询 cursor = session.execute(‘select * from users‘) result = cursor.fetchall() # 添加 cursor = session.execute(‘insert into users(name) values(:value)‘,params={"value":‘wupeiqi‘}) session.commit() print(cursor.lastrowid) """ session.close()
其他
基本增删改查补充
#!/usr/bin/env python # -*- coding:utf-8 -*- import time import threading from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, ForeignKey, UniqueConstraint, Index from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy import create_engine from sqlalchemy.sql import text from db import Users, Hosts engine = create_engine("mysql+pymysql://root:[email protected]:3306/s6", max_overflow=0, pool_size=5) Session = sessionmaker(bind=engine) session = Session() # ################ 添加 ################ """ obj1 = Users(name="wupeiqi") session.add(obj1) #批量添加 session.add_all([ Users(name="wupeiqi"), Users(name="alex"), Hosts(name="c1.com"), ]) session.commit() """ # ################ 删除 ################ """ session.query(Users).filter(Users.id > 2).delete() session.commit() """ # ################ 修改 ################ """ session.query(Users).filter(Users.id > 0).update({"name" : "099"}) session.query(Users).filter(Users.id > 0).update({Users.name: Users.name + "099"}, synchronize_session=False) #字符串 session.query(Users).filter(Users.id > 0).update({"age": Users.age + 1}, synchronize_session="evaluate") #数字 session.commit() """ # ################ 查询 ################ """ r1 = session.query(Users).all() r2 = session.query(Users.name.label(‘xx‘), Users.age).all() #lable #as xx r3 = session.query(Users).filter(Users.name == "alex").all() r4 = session.query(Users).filter_by(name=‘alex‘).all() #如果里面写条件就用filter_by,和上面filter查询是一回事,只是一种不同的方式 r5 = session.query(Users).filter_by(name=‘alex‘).first() r6 = session.query(Users).filter(text("id<:value and name=:name")).params(value=224, name=‘fred‘).order_by(Users.id).all() #查询里面如果有动态传参的时候,吧它包在text里面,:value,:name这样的语法后面用.params来进行格式化 r7 = session.query(Users).from_statement(text("SELECT * FROM users where name=:name")).params(name=‘ed‘).all() #上面的这个方式也可以用这一种 ,直接可以进行SQL语句的查询 """ session.close()
三、SQLAlchemy-Utils
1、由于sqlalchemy中没有提供choice方法,所以借助SQLAlchemy-Utils组件提供的choice方法
import datetime from sqlalchemy import create_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer, String, Text, ForeignKey, DateTime, UniqueConstraint, Index from sqlalchemy.orm import relationship from sqlalchemy_utils import ChoiceType Base = declarative_base() class Xuan(Base): __tablename__ = ‘xuan‘ types_choices = ( (1,‘欧美‘), (2,‘日韩‘), (3,‘老男孩‘), ) id = Column(Integer,primary_key=True,autoincrement=True) name = Column(String(64)) types = Column(ChoiceType(types_choices,Integer())) __table_args__ = { ‘mysql_engine‘:‘Innodb‘, ‘mysql_charset‘:‘utf8‘, } engine = create_engine( "mysql+pymysql://root:[email protected]:3306/ttt2?charset=utf8", max_overflow=0, # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30, # 池中没有线程最多等待的时间,否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收(重置) ) Base.metadata.create_all(engine) 查询: result_list = session.query(Xuan).all() for item in result_list: print(item.types.code,item.types.value)
2、scoped_session
from sqlalchemy.orm import sessionmaker from sqlalchemy import create_engine from sqlalchemy.orm import scoped_session engine = create_engine( "mysql+pymysql://root:[email protected]:3306/ttt?charset=utf8", max_overflow=0, # 超过连接池大小外最多创建的连接 pool_size=5, # 连接池大小 pool_timeout=30, # 池中没有线程最多等待的时间,否则报错 pool_recycle=-1 # 多久之后对线程池中的线程进行一次连接的回收(重置) ) SessionFactory = sessionmaker(bind=engine) # 方式一:由于无法提供线程共享功能,所有在开发时要注意,在每个线程中自己创建 session。 # from sqlalchemy.orm.session import Session # 自己具有操作数据库的:‘close‘, ‘commit‘, ‘connection‘, ‘delete‘, ‘execute‘, ‘expire‘,..... session = SessionFactory() # print(‘原生session‘,session) # 操作 session.close() # 方式二:支持线程安全,为每个线程创建一个session # - threading.Local # - 唯一标识 # ScopedSession对象 # self.registry(), 加括号 创建session # self.registry(), 加括号 创建session # self.registry(), 加括号 创建session from greenlet import getcurrent as get_ident session = scoped_session(SessionFactory,get_ident) # session.add # 操作 session.remove()
3、Flask-SQLAlchemy和Flask-Migrate 组件
4、Flask-SQLAlchemy:吧Flask和SQLAlchemy结合在一起,粘合剂 在__init__.py 文件中 1 引入Flask-SQLAlchemy 中的SQLAlchemy,实例化了一个SQLAlchemy对象 2 注册Flask-SQLAlchemy: - 有两种方式 方式一: 在函数里面,SQLAlchemy(app) #如果想在其他地方使用这种方式就不好使了 方式二: 在全局: db = SQLAlchemy(), 在函数里面 db.init_app(app) #调用init_app方法吧app放进去了 3、导入models的类 4、导入的类中继承了db.model,其实本质上还是继承了Base类 5、manage.py 创建数据库表,可以通过命令来创建。借助Flask-Migrate组件来完成 5、Flask-Migrate: -旧5 被毙掉了:在manage.py里面导入db,以后执行db.create_all()创建表,以后执行drop_all()删除表 这样不好,我们可以和Flask-Migrate结合起来用 -新5:Flask-Migrate - 安装组件:pip install Flask-Migrate - 5.1 导入 from flask_migrate import Migrate, MigrateCommand from app import db, app - 5.2 migrate = Migrate(app,db) #创建实例 - 5.3 创建命令 manager.add_command("db",MigrateCommand) - 5.4 执行命令 python manage.py db init #只执行第一次 python manage.py db migrate python manage.py db upgrade 在执行命令之前,得先连接数据库,他才会知道吧表放在那里,
4、详说注册SQLAlchemy的两种方式
1)方式一
from flask_sqlalchemy import SQLAlchemy from flask import FLask app = Flask(__name__) app.config[‘SQLALCHEMY_DATABASE_URI‘] = "mysql://root:[email protected]/test" db = SQLAlchemy(app)
2)方式二:
from flask_sqlalchemy import SQLAlchemy from flask import FLask db = SQLAlchemy() def create_app(): app = Flask(__name__) db.init_app(app) return app
5、操作数据库
通过上面注册了SQLAlchemy,就直接可以从db.session了
#方式一 db.session #会自动创建一个session db.session.add() db.session.query(models.User.id,models.User.name).all() db.session.commit() db.session.remove() #方式二 导入models models.User.query
6、flask中所有用到过的组件
所有用过的组件 Flask 连接数据库的两种操作 要么DBUtils:用于执行原生SQL的 用自己的util里面的sqlhelper来完成 要么SQLAlchemy:遵循他自己的语法来链接 方式一:SQLAlchemy(app)这种方式有局限性,如果我在其他地方也得用到呢?可以吧它写到全局 方式二:优点, 实例化一下:db = SQLAlchemy() 注册: 在settings里面配置一下数据库链接方式 SQLALCHEMY_DATABASE_URI = "mysql+pymysql://root:[email protected]:3306/s6?charset=utf8" SQLALCHEMY_POOL_SIZE = 2 SQLALCHEMY_POOL_TIMEOUT = 30 SQLALCHEMY_POOL_RECYCLE = -1 Flask-SQLAlchemy: db.init_app(app) Flask-Session #用于吧session保存在其他地方 Flask-Script #生成命令 Flask-Migrate #数据库迁移 Flask-SQLAlchemy #将Flask和SQLAlchemy很好的结合在一起 #本质、:每次操作数据库就会自动创建一个session连接,完了自动关闭 Blinker #信号 Wtforms #FORM组件 用到的组件和版本 pip3 freeze #获取环境中所有安装的模块 pip3 freeze > a.txt pip3 freeze > requirements.txt #pip3 install pipreqs #帮你找到当前程序的所有模块,并且自动生成 requirements.txt文件,写入内容 pipreqs ./ #根目录 以后别人给你一个程序,告知你一个文件夹需要安装的组件:requirements.txt 进入程序目录: pip install -r requirements.txt #就会把设计到的所有的组件就会装上 结构: app static templates views __init__.py models.py
原文地址:https://www.cnblogs.com/liluning/p/8312622.html
时间: 2024-10-29 20:39:21