> > > > > > > > sqlobject.dberrors.OperationalError: no such column: > animal.cage_id > > > > > > > > > > > > > > But there is "cage_id" columnm in the "animal" table > > > > > > > > > > > > Well, that's exactly the problem :) > > > > > > > > > > Are you sure this part of the problem is in SQLObject and not in > > > SQLite? > > > > > (There are probably other problems - inheritance was developed for > > > simple > > > > > use cases and hardly support joins and aggregates...) > > > > > > > > I only guess that the problem is with SQLObject since SQLite itself is > > > > pretty reliable. But I'm getting also more and more convinced that > > > > using inheritance is not a good idea, I ran into other similar > > > > troubles too. So probably it's best to stay away from them. > > > > > > I use inheritance a lot, but I don't usually do JOINs (I just do it the > OO > > > way since I don't have very large sets of data) and it works very well. > > > > > > Hi, can you please test the code below (if you have sqlite)? If you > > use a different db, can you please change the connectionForURI to use > > yours and test then? The correct output should be 5 of course. > > I can't, but I don't see the point. What do you expect me to see running > the test?
Well, if you would have a different db than sqlite and for you the test would pass it would mean that the problem is either with sqlite or the python binding pysqlite, but not sqlobject. > > If you don't use joins, how would you select the total number of > > animals in a zoo in this example? Select (almost) everything and > > filter through them in python? > > For counting: > > count = 0 > for c in the_zoo.cages: > count += len(c.animals) That is of course okay, but it will issue lot of sql queries and the advantage of using joins is that there will only be a single query. So if performance is of concern using joins is advantageous but at the moment I (or anyone else using sqlite) can't use them together with inheritance. > > or: > > count = 0 > for a in animal.select(): > if a.cage.zoo == the_zoo: > count += 1 Here you potentially select a lot more items than necessary, so might also be a problem performance-wise. > For selecting: > > my_list = [a for a in animal.select() if predicate(a)] Same here. I'll try to narrow down where the problem is (a) sqlite (b) pysqlite (c) sqlobject. If anyone else could give the test code a shot with a different db that would be really helpful. Cheers, Daniel ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ sqlobject-discuss mailing list sqlobject-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/sqlobject-discuss
