tornado的ORM

tornado的ORM

---

• 安装sqlalchemy和pymysql
  • pip install sqlalchemy
  • pip install pymysql
• 连接数据库

  •  1 from sqlalchemy import create_engine
     2 
     3 
     4 
     5 config = {
     6     'HOST': '',
     7     'USERNAME': '',
     8     'PASSWORD': '',
     9     'PORT': '',
    10     'DATABASE': '',
    11     'PARAMS': ''
    12 }
    13 
    14 
    15 DB_URL = 'mysql+pymysql://{USERNAME}:{PASSWORD}@{HOST}:{PORT}/{DATABASE}?{PARAMS}'
    16 
    17 engine = create_engine(DB_URL.format(**config))
    18 
    19 
    20 
    21 if __name__ == '__main__':
    22     conc = engine.connect()
    23     result = conc.execute('select 1')
    24     print(result.fetchone())

    如果连接成功，则控制台会出现（1，）的结果

    
    
• 数据库建模
  • 建立base类

     1 from sqlalchemy import create_engine
     2 from sqlalchemy.ext.declarative import declarative_base
     3 
     4 
     5 config = {
     6     'HOST': '',
     7     'USERNAME': '',
     8     'PASSWORD': '',
     9     'PORT': '',
    10     'DATABASE': '',
    11     'PARAMS': ''
    12 }
    13 
    14 
    15 DB_URL = 'mysql+pymysql://{USERNAME}:{PASSWORD}@{HOST}:{PORT}/{DATABASE}?{PARAMS}'
    16 
    17 engine = create_engine(DB_URL.format(**config))
    18 
    19 Base = declarative_base(engine)

  • 使用base类并建立表格

     1 from settings import Base
     2 from sqlalchemy import Column, Integer, String, DateTime, Boolean
     3 from datetime import datetime
     4 
     5 
     6 class User(Base):
     7     __tablename__ = 'user'  # 指定表名
     8     id = Column(Integer, autoincrement=True, primary_key=True)
     9     username = Column(String(20))
    10     password = Column(String(20))
    11     create_time = Column(DateTime, default=datetime.now())
    12     is_login = Column(Boolean, default=False, nullable=False)
    13 
    14 
    15 
    16 
    17 if __name__ == '__main__':
    18     Base.metadata.create_all()  # 创建表格

    创建的表名必须为该类的__tablename__属性，Colum新建一个字段，然后给Colum传参来进行约束

• 简单的增删改查
  • 增

    •  1 from sqlalchemy import create_engine
       2 from settings import DB_CONFIG
       3 from sqlalchemy.ext.declarative import declarative_base
       4 from sqlalchemy.orm import sessionmaker
       5 
       6 
       7 DB_URL = 'mysql+pymysql://{USERNAME}:{PASSWORD}@{HOST}:{PORT}/{DATABASE}?{PARAMS}'
       8 
       9 engine = create_engine(DB_URL.format(**DB_CONFIG))
      10 
      11 Base = declarative_base(engine)
      12 
      13 Session = sessionmaker(engine)
      14 
      15 session = Session()

      与上面不同的是,新建了一个Session对象，然后将这个对象实例化，接下来的数据库操作都用到这个实例对象来操作

    •  1 from config import Base
       2 from sqlalchemy import Column, Integer, String, DateTime, Boolean
       3 from datetime import datetime
       4 
       5 class User(Base):
       6     __tablename__ = 'user'
       7     id = Column(Integer, primary_key=True, autoincrement=True)
       8     username = Column(String(20))
       9     password = Column(String(20))
      10     create_time = Column(DateTime, default=datetime.now())
      11     is_login = Column(Boolean, default=False, nullable=False)
      12 
      13

      表结构

    •  1 from wechat import User
       2 from config import session
       3 
       4 def add():
       5     user = User(username='ivy', password='123456')
       6     session.add(user)
       7     session.commit()
       8 
       9 
      10 if __name__ == '__main__':
      11     add()

      添加一条

    •  1 from wechat import User
       2 from config import session
       3 
       4 def add():
       5 
       6     session.add_all([
       7         User(username='ivy', password='123456'),
       8         User(username='ivy1', password='123456'),
       9         User(username='ivy2', password='123456'),
      10     ])
      11     session.commit()
      12 
      13 
      14 if __name__ == '__main__':
      15     add()

      添加多条

  • 查

    •  1 from wechat import User
       2 from config import session
       3 
       4 def search():
       5     session.query(User).all()  # 查找所有
       6     result = session.query(User).first().username  # 查找第一个
       7     result = session.query(User).filter(User.username=='ivy').first().password
       8     print(result)
       9 
      10 
      11 
      12 if __name__ == '__main__':
      13     search()

  • 改

    •  1 from wechat import User
       2 from config import session
       3 
       4 
       5 def update():
       6     session.query(User).filter(User.username == 'ivy').update(
       7         {
       8             User.username: 'bob',
       9             User.password: '123654',
      10         }
      11     )
      12     session.commit()
      13 
      14 
      15 if __name__ == '__main__':
      16     update()

      更改的数据以字典的键值对的形式传入

  • 删

    •  1 from wechat import User
       2 from config import session
       3 
       4 
       5 def delete():
       6     result = session.query(User).filter(User.username == 'bob').first()
       7 
       8     session.delete(result)
       9     session.commit()
      10 
      11 
      12 if __name__ == '__main__':
      13     delete()

      先查询结果，再讲查询的结果删除，如果查询的结果为空，则删除会报错。