How to convert query(exists()...) to SQLAlchemy 2 syntax?

[mcarans]

I have been trying to convert the following to SQLAlchemy 2 syntax:

                                if self.session.query(
                                    exists().where(
                                        and_(
                                            DBResource.id == resource_id,
                                            DBResource.md5_hash == hash,
                                        )
                                    )
                                ).scalar():

If I change query to execute, I get an error "Executable SQL or text() construct expected, got <sqlalchemy.sql.selectable.Exists object...".

I'm not sure what I need to do to transform this to SQLAlchemy 2 syntax. Please advise.

[zzzeek]

you want to put the exists() inside of a select()

 stmt = select(exists().where(and_(...)))

run that

result = session.scalar(stmt)

[aalvrz]

@zzzeek How to do this with multiple joins on different tables?

[CaselIT]

It's not really different that just generating a select. It should have join method.