Hi,
I'm working with SQLAlchemy and Postgres and I have a polymorphic model
whose subclasses have a field with the same name. To allow this field to
co-exist with the others and not cause any name conflicts, I'm using the
`declare_attr` decorator from SQLAlchemy.
This solution works well for fields consisting of primary data types,
however when I try to use Postgres's HSTORE to store dictionary values,
SQLAlchemy complains with:
sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) can't adapt
type 'dict'
My guess is that this happens because `declared_attr` has constrains on
which data types its fields have.
Here's an example of how my models look:
*import enum *
*import sqlalchemy as sa*
*from sqlalchemy.dialects.postgres import ARRAY, HSTORE*
*from sqlalchemy.ext.mutables import MutableDict*
*class ChildType(enum.Enum):*
* sub_1 = "sub_1"*
* sub_2 = "sub_2"*
* sub_3 = "sub_3"*
*class ParentModel(sa.declarative_base()):*
* __table__ = 'parent'*
* general_field = sa.Column(sa.String)*
* r_type = sa.Column(sa.Enum(ChildType))*
* __mapper_args__ = {*
* 'polymorphic_identity': 'parent',*
* 'polymorphic_on': resource_type*
* }*
*class Sub1(ParentModel):*
* @sa.declared_attr*
* def child_value(cls):*
* return ParentModel.__table__.c.get('child_value',
sa.Column(sa.Integer, nullable=True))*
* __mapper_args__ = {*
* 'polymorphic_identity': ChildType.sub_1*
* }*
*class Sub2(ParentModel):*
* @sa.declared_attr*
* def child_value(cls):*
* return ParentModel.__table__.c.get('child_value',
sa.Column(sa.Boolean, nullable=True))*
* __mapper_args__ = {*
* 'polymorphic_identity': ChildType.sub_2*
* }*
*class Sub3(ParentModel):*
* @sa.declared_attr*
* def child_value(cls):*
* return ParentModel.__table__.c.get('child_value',
sa.Column(ARRAY(MutableDict.as_mutable(HSTORE))))*
* __mapper_args__ = {*
* 'polymorphic_identity': ChildType.sub_3*
* }*
Can anyone help me out with a potential workaround/solution?
Thanks!
--
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