def create_clock(self, entity, period=effective_now()):
"""creates a new clock for a temporal model.
"""
clock = entity._clock()
clock.effective = period
clock.entity = entity
clock.ticks = 0
# self.add(clock)
return clock
def create_clock_bulk(self, entity, period=effective_now()):
"""creates a new clock for a temporal model.
"""
clock = entity._clock()
clock.rid = uuid4()
clock.effective = period
clock.entity_id = entity.rid
clock.ticks = 0
return clock, True
def get_or_create_clock(self, entity, period=effective_now()):
"""gets an existing or creates a new entity clock
for a temporal model.
"""
if entity.rid:
clock = self.query(entity.__class__).clock(entity, period)
if clock:
return clock, False
return self.create_clock(entity, period), True
def get_or_create_clock_entity(entity, period=effective_now()):
"""Tries to retrieve an entity clock for the given period
from the database. If it does not exist, a new clock is
created.
"""
clock_cls = entity._clock
clock_entity = session.query(clock_cls)\
.filter(
clock_cls.effective.contains(period),
clock_cls.entity_id == entity.rid
).one_or_none()
if not clock_entity:
clock_entity = clock_cls()
clock_entity.effective = period
clock_entity.entity = entity
clock_entity.ticks = 0
session.add(clock_entity)
return clock_entity
def clock(self, entity, period=effective_now()):
cls = entity._clock
return self.session.query(cls).filter(
cls.effective.contains(period),
cls.entity_id == entity.rid).one_or_none()