[英]Flask-SqlAlchemy Adjacency List Relationship backfref unexpected error
[英]SQLAlchemy adjacency list relationship with declared attributes
我有一個由不同類型的子代繼承的頂級模型聲明
class HasId(object):
@declared_attr
def id(cls):
return Column('id', Integer, Sequence('test_id_seq'), primary_key=True)
...
@declared_attr
def triggered_by_id(cls):
return Column(Integer, ForeignKey('tests.id'), nullable=True)
@declared_attr
def triggered(cls):
return relationship('TestParent',
foreign_keys='TestParent.triggered_by_id',
lazy='joined',
cascade='save-update, merge, delete, delete-orphan',
backref=backref('triggered_by', remote_side=[id])
)
class TestParent(HasId, Model):
__tablename__ = 'tests'
discriminator = Column(String(50))
__mapper_args__ = {'polymorphic_on': discriminator}
class FooTest(TestParent):
__tablename__ = 'footests'
__mapper_args__ = {'polymorphic_identity': 'footests'}
id = Column(Integer, ForeignKey('tests.id'), primary_key=True)
bar = Column(Boolean)
...
當IO嘗試構建此數據庫時,我收到一個錯誤,該錯誤是由於我如何在backref
關系上定義backref
的remote_side
triggered_by
。
完整的錯誤是
ArgumentError: Column-based expression object expected for argument 'remote_side'; got: '<built-in function id>', type <type 'builtin_function_or_method'>
解決方案是將backref
定義從
backref('triggered', remote_side=[id])
至
backref('triggered', remote_side='TestParent.id')
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