On Sat, Aug 22, 2020, at 12:36 PM, Saakshaat Singh wrote: > I agree that it's not practical for saving columns with the same name but in > our case, we had to give the child subclasses the same column names. > SQLAlchemy has declared_attr > <https://www.kite.com/python/docs/sqlalchemy.ext.declarative.declared_attr> > which converts the columns to scalar objects allowing the database to hold > different columns with the same name (making it possible only for polymorphic > models). > > I hope that helps! Let me know if you have any more questions.
unfortunately not. Your example illustrates only a single table named "parent". I have no information on the actual database schema you are attempting to map towards. The MCVE ( see link at the bottom of this email) is a means of communicating exactly the code that fails to run and how the error is produced. Within the SQLAlchemy team it's not a good use of our time to try to guess what it is someone is trying to do so we ask that users illustrate everything up front to reproduce the error. thanks! > On Saturday, August 22, 2020 at 9:30:11 AM UTC-7 Mike Bayer wrote: >> __ >> If your model is based all on one table called "parent", it can only have >> one column called "child_value" and it can only be of a single database >> type, since that's your CREATE TABLE. I'm not able to follow what your >> example intends to do as you seem to be creating many Column objects with >> the same name and different types, all against a single table. That's not >> possible in relational databases. >> >> >> On Sat, Aug 22, 2020, at 12:18 PM, Mike Bayer wrote: >>> 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 >>>> description. >>>> --- >>>> You received this message because you are subscribed to the Google Groups >>>> "sqlalchemy" group. >>>> To unsubscribe from this group and stop receiving emails from it, send an >>>> email to sqlalchemy+...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/sqlalchemy/0421937b-08f0-470d-8067-43430bfc1ca8n%40googlegroups.com >>>> >>>> <https://groups.google.com/d/msgid/sqlalchemy/0421937b-08f0-470d-8067-43430bfc1ca8n%40googlegroups.com?utm_medium=email&utm_source=footer>. >>> >>> >>> -- >>> 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. >>> --- >>> You received this message because you are subscribed to the Google Groups >>> "sqlalchemy" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to sqlalchemy+...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/sqlalchemy/51688c7d-cca2-433a-8690-f0996ce5f8a7%40www.fastmail.com >>> >>> <https://groups.google.com/d/msgid/sqlalchemy/51688c7d-cca2-433a-8690-f0996ce5f8a7%40www.fastmail.com?utm_medium=email&utm_source=footer>. >> > > -- > 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. > --- > You received this message because you are subscribed to the Google Groups > "sqlalchemy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sqlalchemy+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sqlalchemy/be12a2bb-81bc-439b-b178-f7fc4300ce67n%40googlegroups.com > > <https://groups.google.com/d/msgid/sqlalchemy/be12a2bb-81bc-439b-b178-f7fc4300ce67n%40googlegroups.com?utm_medium=email&utm_source=footer>. -- 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. --- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. 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