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))
class User(UserMixin, Base):
__tablename__ = 'user'
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