On Jan 3, 2012, at 3:31 PM, sector119 wrote: > Hello. > > Can't get this to work, I want to get users who is online - users where > last_read column <= now() - 30 minutes > With DBSession.query(User).filter(User.is_online) query > > But get the following error: > > File "/home/eps/devel/tourclub/pbb/pbb/models/__init__.py", line 147, in > <module> > class User(UserMixin, Base): > File > "/home/eps/devel/tourclub/sqlalchemy/lib/sqlalchemy/ext/declarative.py", line > 1273, in __init__ > _as_declarative(cls, classname, cls.__dict__) > File > "/home/eps/devel/tourclub/sqlalchemy/lib/sqlalchemy/ext/declarative.py", line > 1078, in _as_declarative > column_copies[obj] = getattr(cls, name) > File > "/home/eps/devel/tourclub/sqlalchemy/lib/sqlalchemy/ext/declarative.py", line > 1480, in __get__ > return desc.fget(cls) > File "/home/eps/devel/tourclub/pbb/pbb/models/__init__.py", line 143, in > is_online > return column_property(case([(cls.last_read is not None, cls.last_read <= > func.now() - datetime.timedelta(minutes=30))], else_=False)) > File > "/home/eps/devel/tourclub/sqlalchemy/lib/sqlalchemy/sql/expression.py", line > 607, in case > return _Case(whens, value=value, else_=else_) > File > "/home/eps/devel/tourclub/sqlalchemy/lib/sqlalchemy/sql/expression.py", line > 3016, in __init__ > _literal_as_binds(r)) for (c, r) in whens > File > "/home/eps/devel/tourclub/sqlalchemy/lib/sqlalchemy/sql/expression.py", line > 1410, in _no_literals > "bound value." % element) > sqlalchemy.exc.ArgumentError: Ambiguous literal: True. Use the 'text()' > function to indicate a SQL expression literal, or 'literal()' to indicate a > bound value. > > > I want to get something like this but in SA... > > SELECT * FROM "user" u WHERE (CASE WHEN u.last_read IS NULL THEN False ELSE > u.last_read <= now() - 30 * INTERVAL '1 minute' END) IS True; > > > I use next UserMixin class and User declarative model: > > class UserMixin(object): > id = Column(Integer, primary_key=True) > username = Column(String(255), unique=True, nullable=False) > ... > last_read = Column(DateTime) > > @declared_attr > def is_online(cls): > return column_property(case([(cls.last_read is not None, > cls.last_read <= func.now() - datetime.timedelta(minutes=30))], else_=False))
you'd need to say "cls.last_read != None" to produce "IS NOT NULL". You might need else_=literal(False) too. -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@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.
