sqlalchemy数据模型

sqlalchemy在python里作为orm还是比较有名气的，以下是建立的几个简单模型，完全可和flask的数据持久层分离。

 # coding: utf8
 from sqlalchemy import Column, String, Integer, DateTime, BigInteger, Numeric, ForeignKey, SmallInteger, create_engine
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import create_session, relationship

 Base = declarative_base()
 _db_session = None

 def get_engine():
     return create_engine('mysql+pymysql://root:1234@localhost/wms?charset=utf8', echo=True)

 def get_session():
     if _db_session is None:
         engine = get_engine()
         return create_session(engine)
     else:
         return _db_session

 def create_all():
     engine = get_engine()
     Base.metadata.create_all(engine)

 def drop_all():
     engine = get_engine()
     Base.metadata.drop_all(engine)

 class Role(Base):
     __tablename__ = 'a_role'
     code = Column(String(20), primary_key=True)
     label = Column(String(50))

 class User(Base):
     __tablename__ = 'a_user'
     id = Column(BigInteger, primary_key=True)
     code = Column(String(20), nullable=False, index=True, unique=True)
     label = Column(String(50))
     pwd = Column(String(50))
     create_date = Column(DateTime)
     memo = Column(String(50))
     role_code = Column(String(20), ForeignKey('a_role.code'))
     role = relationship('Role', backref='users')

 class SupplierClass(Base):
     __tablename__ = 'a_supplier_class'
     code = Column(String(30), primary_key=True)
     label = Column(String(50))

 class Supplier(Base):
     __tablename__ = 'a_supplier'
     id = Column(BigInteger, primary_key=True)
     code = Column(String(30), index=True)
     label = Column(String(50))
     tel = Column(String(30))
     address = Column(String(50))
     contacts = Column(String(30))
     level = Column(SmallInteger)
     create_date = Column(DateTime)
     memo = Column(String(50))
     class_code = Column(String(30), ForeignKey('a_supplier_class.code'))
     supplier_class = relationship('SupplierClass', backref='suppliers')

 class Warehouse(Base):
     __tablename__ = 'a_warehouse'
     code = Column(String(30), primary_key=True)
     label = Column(String(50))
     address = Column(String(50))
     create_date = Column(DateTime)
     memo = Column(String(50))
     manager_id = Column(BigInteger, ForeignKey('a_user.id'))
     manager = relationship('User')

 class LocationClass(Base):
     __tablename__ = 'a_location_class'
     code = Column(String(30), primary_key=True)
     label = Column(String(50))

 class Location(Base):
     __tablename__ = 'a_location'
     id = Column(BigInteger, primary_key=True)
     code = Column(String(30), index=True)
     label = Column(String(50))
     max_qty = Column(Numeric(10, 2))
     create_date = Column(DateTime)
     memo = Column(String(50))
     warehouse_code = Column(String(30), ForeignKey('a_warehouse.code'))
     manager_id = Column(BigInteger, ForeignKey('a_user.id'))
     class_code = Column(String(30), ForeignKey('a_location_class.code'))
     manager = relationship('User')
     warehouse = relationship('Warehouse')
     location_class = relationship('LocationClass')

 class ItemClass(Base):
     __tablename__ = 'a_item_class'
     code = Column(String(30), primary_key=True)
     label = Column(String(50))

 class Item(Base):
     __tablename__ = 'a_item'
     id = Column(BigInteger, primary_key=True)
     code = Column(String(30), index=True)  # 物料代码
     label = Column(String(100))  # 品名
     type = Column(SmallInteger)  # 0原材料，1半成品，2成品
     class_code = Column(String(30), ForeignKey('a_item_class.code'))
     location_id = Column(BigInteger, ForeignKey('a_location.id'))
     item_class = relationship('ItemClass')  # 物料分类
     location = relationship('Location')  # 推荐库位
     safety_stock = Column(Numeric(10, 2))  # 安全库存
     mpq = Column(Numeric(10, 2))  # 最小包装数量
     create_date = Column(DateTime)
     memo = Column(String(50))

 # drop_all()
 # create_all()