hey Michael -
What looks to be happening there is you're making an INSERT against the Table
object for Event, the columns in this Table object are: "id", "start_date".
The Table has no information about "start_time" as that is an ORM construct
only. so your first example is equivalent towards:
table = Table("event", meta, Column("id", BigInteger), Column("start_date",
DateTime))
stmt = table.insert().values(start_time=utcnow())
see the problem?
your second example which provides the actual "Event.start_time" attribute as a
key allows SQLAlchemy to resolve that attribute into the Column it refers
towards which is the Event.__table__.c.start_date column object.
Ideally if the insert() were against the Event ORM entity directly, the ORM
would be smart enough to figure this out as in SQLAlchemy 1.4 we have
ORM-enabled Core constructs, but currently insert() is the one that is not
implemented right now. so maybe someday!
On Tue, Dec 22, 2020, at 3:16 AM, Michael Merickel wrote:
> Is there a way to make the following insert statement work by changing
> something in the Event object's definition? Note I've simplified the example,
> the reasons for using the core constructs in the first place are to use
> postgres ON CONFLICT directives with it otherwise yes I could simply use the
> ORM where the synonyms would work fine.
>
> class Event(Base):
> id = Column(BigInteger, primary_key=True)
> start_date = Column(DateTime)
> start_time = synonym('start_date')
>
> dbsession.execute(insert(Event.__table__).values(start_time=datetime.utcnow()).returning(Event.id)).scalar()
>
> Error raised, presumably because a core insert construct doesn't support
> column aliases defined at the mapper level?
>
> sqlalchemy.exc.CompileError: Unconsumed column names: start_time
>
> Thanks!
>
> - Michael
>
>
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