So I am trying to do the following:
class SimpleModel(object):
__table_args__ = {'extend_existing': True}
id = db.Column(db.Integer, primary_key=True)
class GroupEntityAttributes(SimpleModel, db.Model):
__table_args__ = {'extend_existing': True}
__tablename__ = 'group_entity'
#Table Columns
id = db.Column(db.Integer, primary_key=True)
group_id = db.Column(db.Integer, db.ForeignKey('groups.id'), nullable=
False)
entity_id = db.Column(db.Integer, db.ForeignKey('entities.id'), nullable
=False)
key = db.Column(db.String)
value = db.Column(db.Text)
#Relationships
entity = db.relationship('Entity', lazy='joined')
group = db.relationship('Group')
class GroupEntityAttributesPoly(GroupEntityAttributes):
__mapper_args__ = {'polymorphic_on': GroupEntityAttributes.key}
class GroupEntity(GroupEntityAttributesPoly):
__mapper_args__ = {'polymorphic_identity': '_has_connection'}
others = db.relationship(
'GroupEntityAttributes',
primaryjoin=and_(
remote(foreign(GroupEntityAttributes.group_id)) ==
GroupEntityAttributes.group_id,
remote(foreign(GroupEntityAttributes.entity_id)) ==
GroupEntityAttributes.entity_id,
)
)
When I try to load the model GroupEntity I get an error:
ArgumentError: Can't determine relationship direction for relationship '
GroupEntity.others' - foreign key columns within the join condition are
present in both the parent and the child's mapped tables. Ensure that only
those columns referring to a parent column are marked as foreign, either
via the foreign() annotation or via the foreign_keys argument.
I am not sure how to overcome this error. Would appreciate any help.
Best,
Anton.
On Tuesday, September 9, 2014 1:10:40 PM UTC-7, Anton wrote:
>
> Trying to use with multiple table mapping.
>
> On Tuesday, September 9, 2014 1:03:25 PM UTC-7, Anton wrote:
>>
>> Hi,
>>
>> I need some help choosing the right pattern for the models I have. I have
>> the following tables:
>> Entity (INT id, VARCHAR name)
>> Group (INT id, VARCHAT name)
>> GroupEntityAttributes(INT entity_id, INT group_id, VARCHAR key, VARCHAR
>> name)
>>
>> Entity and Group models are pretty straight forward. But
>> GroupEntityAttributes represents Entity within some group with custom
>> attributes added, so it resembles this pattern (
>> https://bitbucket.org/zzzeek/sqlalchemy/src/374173e89d4e21a75bfabd8a655d17c247b6f1fc/examples/vertical/dictlike.py?at=master
>>
>> ), the only difference is that there is an additional foreign key.
>> I wonder if there is any approach I can use to adapt vertical pattern for
>> my needs without modifying tables.
>>
>> Best,
>> Anton.
>>
>>
>>
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