擅长:python、mysql、java
<p>您还可以声明性地执行此操作。</p>
<p>下面是一个基于上述代码的类似示例,我确实使用了backref。</p>
<pre><code>VolumeRelationship = Table(
'VolumeRelationship', Base.metadata,
Column('ParentID', Integer, ForeignKey('Volumes.ID')),
Column('VolumeID', Integer, ForeignKey('Volumes.ID'))
)
class Volume(Base):
""" Volume Object """
__tablename__ = "Volumes"
id = Column('ID', Integer, primary_key=True, nullable=False)
type = Column('Type', String(25))
name = Column('Name', String(25))
poolid = Column('pool', Integer, ForeignKey('Pools.ID'))
parents = relation(
'Volume',secondary=VolumeRelationship,
primaryjoin=VolumeRelationship.c.VolumeID==id,
secondaryjoin=VolumeRelationship.c.ParentID==id,
backref="children")
</code></pre>