Python的SQLAlchemy框架使用入门

[
  ('1', 'Michael'),
  ('2', 'Bob'),
  ('3', 'Adam')
]

class User(object):
  def __init__(self, id, name):
    self.id = id
    self.name = name

[
  User('1', 'Michael'),
  User('2', 'Bob'),
  User('3', 'Adam')
]

$ easy_install sqlalchemy

# 导入:
from sqlalchemy import Column, String, create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base

# 创建对象的基类:
Base = declarative_base()

# 定义User对象:
class User(Base):
  # 表的名字:
  __tablename__ = 'user'

  # 表的结构:
  id = Column(String(20), primary_key=True)
  name = Column(String(20))

# 初始化数据库连接:
engine = create_engine('mysql+mysqlconnector://root:password@localhost:3306/test')
# 创建DBSession类型:
DBSession = sessionmaker(bind=engine)

class School(Base):
  __tablename__ = 'school'
  id = ...
  name = ...

# 创建session对象:
session = DBSession()
# 创建新User对象:
new_user = User(id='5', name='Bob')
# 添加到session:
session.add(new_user)
# 提交即保存到数据库:
session.commit()
# 关闭session:
session.close()

# 创建Session:
session = DBSession()
# 创建Query查询，filter是where条件，最后调用one()返回唯一行，如果调用all()则返回所有行:
user = session.query(User).filter(User.id=='5').one()
# 打印类型和对象的name属性:
print 'type:', type(user)
print 'name:', user.name
# 关闭Session:
session.close()

type: <class '__main__.User'>
name: Bob

class User(Base):
  __tablename__ = 'user'

  id = Column(String(20), primary_key=True)
  name = Column(String(20))
  # 一对多:
  books = relationship('Book')

class Book(Base):
  __tablename__ = 'book'

  id = Column(String(20), primary_key=True)
  name = Column(String(20))
  # “多”的一方的book表是通过外键关联到user表的:
  user_id = Column(String(20), ForeignKey('user.id'))