Martin Aspeli wrote: > > How would the mapper configuration look if it were an expression? If it > were a column?
this is the `polymorphic_on` attribute. It generally expects to point to a column. Its not yet very flexible for expressions which is a TODO. an actual column in your base table (and each table which you'd like to do polymorphic queries) would accomplish the desired result. > >>> - I've had to repeat all the fields from the base class in the >>> sub-classes. Otherwise, I'd get errors using those attributes, even >>> though VehicleCar and VehicleBus both inherits form Vehicle. >> >> Well SQLA doesn't have any direct support for PG INHERITS, and the fact >> is >> that concrete inherits means that each Table repeats each common column >> specifically - one reason why concrete inheritance is widely considered >> to >> be the most cumbersome form of relational inheritance. There was a trac >> ticket requesting that the columns "inherit" the way they do with a >> simpler single- or joined- table setup, but at the end of the day that >> request was asking for some very complex magic to occur. Your database >> expresses distinct columns at the public DDL level, even though INHERITS >> means theyre the "same", so SQLA keeps it simple and would like you to >> express them in the same way as what it will see when talking to the DB. > > True, except I think it's superflos. I could do this in Postgres too: its superfluous except that SQLA wants to keep things simple and not guess things about your schema. theres a request which I closed here: http://www.sqlalchemy.org/trac/ticket/1469 -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
