在sqlalchemy中交叉数据库加入

Question

SQLAlchemy中有没有办法进行跨数据库连接.具体来说,这是我的用例:

架构

1. db1.entity1
   1. entity1_id:主键
   2. entity2_id:db2.entity2.entity2_id的外键
2. db2.entity2
   1. entity2_id:主键

模型

我正在为模型使用声明式样式.

class Entity1(Base):
  __tablename__ = 'entity1' ## I tried combination of <db>.<table> with no success
  entity1_id = Column(Integer, primary_key=True)
  entity2_id = Column(Integer, ForeignKey('db2.entity2.entity2_id'))
  entity2 = relationship('Entity2')

class Entity2(Base):
  __tablename__ = 'entity2' ## I tried combination of <db>.<table> with no success
  entity2_id = Column(Integer, primary_key=True)

现在,正如预期的那样,我对Entity1的查询失败,并显示MySQL错误消息,表示找不到表entity2.我尝试了许多不同的组合但__tablename__没有成功.所以我想知道SQLAlchemy是否可行.

Answer 1

您可能需要将schema参数传递给sqlalchemy.schema.Table.使用声明性基础进行ORM映射时,可以通过__table_args__类的属性提供此额外参数.

class Entity2(Base):
    __tablename__ = 'entity2' ## I tried combination of <db>.<table> with no success
    __table_args__ = {'schema': 'db2'}
    entity2_id = Column(Integer, primary_key=True) 

class Entity1(Base):
    __tablename__ = 'entity1' ## I tried combination of <db>.<table> with no success
    __table_args__ = {'schema': 'db1'}
    entity1_id = Column(Integer, primary_key=True)
    entity2_id = Column(Integer, ForeignKey(Entity2.entity2_id))
    entity2 = relationship('Entity2')