Yep, much nicer:
def add_constraints(mapper, class_):
table = class_.__table__
elements = [('period', '&&')]
for col in table.primary_key.columns:
if col.name!='period':
elements.append((col, '='))
table.append_constraint(ExcludeConstraint(*elements))
table.append_constraint(CheckConstraint("period != 'empty'::tsrange"))
listen(Temporal, 'instrument_class', add_constraints, propagate=True)
Where's that propagate option documented?
Chris
On 24/05/2013 15:17, Michael Bayer wrote:
I would apply a single event listener to Temporal, and do all the work of
adding the constraints and all that in the one event handler. I'd skip
__table_args__.
If you're on 0.8, you can apply listeners to mixins and unmapped classes using
"propagate=True", and the events should trigger for all subclasses.
On May 23, 2013, at 7:49 AM, Chris Withers <[email protected]> wrote:
Hi All,
I have a mixin defined like this:
def add_exclude_constraint(mapper, class_):
table = class_.__table__
elements = [('period', '&&')]
for col in table.primary_key.columns:
if col.name!='period':
elements.append((col, '='))
table.append_constraint(ExcludeConstraint(*elements))
class Temporal(object):
@declared_attr
def __table_args__(cls):
listen(cls, 'instrument_class', add_exclude_constraint)
return (
CheckConstraint("period != 'empty'::tsrange"),
)
period = Column(DateTimeRange(), nullable=False, primary_key=True)
That listen call is the source of the dirty feeling...
What's the "right" way to do this?
Chris
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