Is there some compelling reason you wouldn't just install the PostGIS extensions? Assuming there is...
You could use a TEXT column to store WKT values or a BLOB/bytea column to store WKB representations, and perhaps use hybrid_attributes <http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/hybrid.html> to manage the conversion, but realize that because (without PostGIS) the DB doesn't semantically understand these types, so you won't be able to filter against them (other than IS [NOT] NULL) or use them in any meaningful SQL expressions. You'll likely be limited to CRUD capabilities. Actually, now that I think about it, since you won't be able to use them in query expressions anyway, there's probably no reason to go to the extra effort of hybrid properties; just make a pure python property to do the conversion between the mapped TEXT|BLOB column and the Geometry types. But again, trying to use geo types in PostgreSQL without PostGIS just kinda sounds like self-flagellation. :) Ian On Friday, September 4, 2015 at 6:59:29 PM UTC-4, Demitri Muna wrote: > > Hi, > > Is there a way to use the native PostgreSQL (i.e. not postgis) "polygon" > data type through SQLAlchemy? I'm guessing one might be able to define the > model class via autoload as normal, then add some kind of custom column > definition? Surely someone has done this before, but I haven't been able to > find an example. > > I've taken a look at geoalchemy and tried to implement that, but was > getting this error: > > ProgrammingError: (psycopg2.ProgrammingError) function > st_asbinary(polygon) does not exist > LINE 1: ....sdss_frame.filename AS muna_sdss_frame_filename, ST_AsBinar... > ^ > HINT: No function matches the given name and argument types. You might > need to add explicit type casts. > > If at all possible, I'd prefer to use the native data type, even if it > requires a custom adaptor. (Again, surely someone has written this?) > > Cheers, > Demitri > -- 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
