Hi, I have no idea what the problem is and would need a fully runnable MCVE.
Below is part of your test which I've tried to get running but it still errors
out on identifiers missing and such, additionally I need a working example of
exactly the session operations you are trying to achieve. It might be easier
to post the working code example as a github question:
https://github.com/sqlalchemy/sqlalchemy/issues
code so far below:
import enum
import sqlalchemy as sa
from sqlalchemy.dialects.postgresql import ARRAY
from sqlalchemy.dialects.postgresql import HSTORE
from sqlalchemy.ext.mutable import MutableDict
from sqlalchemy.ext.declarative import declarative_base
class ChildType(enum.Enum):
sub_1 = "sub_1"
sub_2 = "sub_2"
sub_3 = "sub_3"
class ParentModel(declarative_base()):
__table__ = "parent"
general_field = sa.Column(sa.String)
resource_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}
e = create_engine("postgresql://scott:tiger@pg12/test", echo=True)
ParentModel.drop_all(e)
ParentModel.create_all(e)
s = Session(e)
s.add(Sub3(child_value=[{"foo": "bar"}]))
s.commit()
On Fri, Aug 21, 2020, at 8:06 PM, Saakshaat Singh wrote:
> 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!
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
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SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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