On Wed, Aug 21, 2019, at 1:46 PM, Michael P. McDonnell wrote:
> Hey team -
>
> I've went through the docs, and likely because I'm a bit of a hack - I'm
> finding it hard to find my answers (because I'm not sure what I'm
> specifically looking to "do" other than "make it work")
>
> So I have the following situation:
> I have a GAME table (with a corresponding LANGUAGE table) - because my users
> might play games.
> *game_language_table = Table(
> 'game_language',
> Base.metadata,
> Column('game_id', UUID(as_uuid=True), ForeignKey('game.id'),
> primary_key=True, nullable=False),
> Column('language_id', String(length=255), ForeignKey('language.id'),
> primary_key=True, nullable=False),
> Column('name', String(length=255), nullable=False, unique=True))
>
> game_table = Table(
> 'game',
> Base.metadata,
> Column('id', UUID(as_uuid=True), primary_key=True, nullable=False,
> default=sqlalchemy.text('uuid_generate_v4()'),
> server_default=sqlalchemy.text('uuid_generate_v4()')),
> Column('join_code', String(length=8), nullable=False, unique=True))
*
> I also have a ROUND table which is effectively just an extension of a game,
> but with a sequence number. Basically - if I have a collection of games that
> I want users to play - they play them as "Rounds" in a given order.
> *round_table = Table(
> 'round',
> Base.metadata,
> Column('id', UUID(as_uuid=True), primary_key=True, nullable=False,
> default=sqlalchemy.text('uuid_generate_v4()'),
> server_default=sqlalchemy.text('uuid_generate_v4()')),
> Column('tournament_id', UUID(as_uuid=True), ForeignKey('tournament.id'),
> nullable=False),
> Column('game_id', UUID(as_uuid=True), ForeignKey('game.id'), nullable=False),
> Column('sequence', Integer, nullable=False, default=0),
> UniqueConstraint('tournament_id', 'sequence'))
*
> So my GAME table has an "id" field, and my round table has a game_id field,
> and an id field.
>
> When I try to join(game_table, round_table) - I get the following error:
> *Implicitly combining column round.id with column game.id under attribute
> 'id'. Please configure one or more attributes for these same-named columns
> explicitly.*
join() does not emit that error; that error occurs when you create a mapping to
the join using either mapper() or a declarative base, since "attribute" refers
to ORM mapped attribute. Mapping to joins with same-named columns is
demonstrated at
https://docs.sqlalchemy.org/en/13/orm/nonstandard_mappings.html#mapping-a-class-against-multiple-tables
.
>
> So - because there's multiple points of entry into these tables: Editing a
> Game is a direct thing, editing a round (which also edits its underlying
> game) is also a direct thing.
>
> How do I craft the JOIN so I don't step on toes?
>
> I tried doing the following:
> *round_join = join(round_table, game_join.alias('game'))*
> That didn't help, because game_id still squashes between game_language and
> round.
>
> Is there a smarter way to go about this?
>
> --
> 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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--
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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