def flush(self, session, objects=None):
# this context will track all the objects we want to save/update/delete,
# and organize a hierarchical dependency structure. it also handles
# communication with the mappers and relationships to fire off SQL
# and synchronize attributes between related objects.
echo = logging.is_info_enabled(self.logger)
flush_context = UOWTransaction(self, session)
# create the set of all objects we want to operate upon
if objects is not None:
# specific list passed in
objset = util.Set(objects)
else:
# or just everything
objset = util.Set(self.identity_map.values()).union(self.new)
# detect persistent objects that have changes
dirty = self.locate_dirty()
# store objects whose fate has been decided
processed = util.Set()
# put all saves/updates into the flush context. detect orphans and throw them into deleted.
for obj in self.new.union(dirty).intersection(objset).difference(
self.deleted):
if obj in processed:
continue
if object_mapper(obj)._is_orphan(obj):
for c in [obj] + list(
object_mapper(obj).cascade_iterator('delete', obj)):
if c in processed:
continue
flush_context.register_object(c, isdelete=True)
processed.add(c)
else:
flush_context.register_object(obj)
processed.add(obj)
# put all remaining deletes into the flush context.
for obj in self.deleted:
if (objset is not None and not obj in objset) or obj in processed:
continue
flush_context.register_object(obj, isdelete=True)
trans = session.create_transaction(autoflush=False)
flush_context.transaction = trans
try:
flush_context.execute()
except:
trans.rollback()
raise
trans.commit()
flush_context.post_exec()
def register_object(self,
obj,
isdelete=False,
listonly=False,
postupdate=False,
post_update_cols=None,
**kwargs):
"""adds an object to this UOWTransaction to be updated in the database.
'isdelete' indicates whether the object is to be deleted or saved (update/inserted).
'listonly', indicates that only this object's dependency relationships should be
refreshed/updated to reflect a recent save/upcoming delete operation, but not a full
save/delete operation on the object itself, unless an additional save/delete
registration is entered for the object."""
#print "REGISTER", repr(obj), repr(getattr(obj, '_instance_key', None)), str(isdelete), str(listonly)
# if object is not in the overall session, do nothing
if not self.uow._is_valid(obj):
return
mapper = object_mapper(obj)
self.mappers.add(mapper)
task = self.get_task_by_mapper(mapper)
if postupdate:
task.append_postupdate(obj, post_update_cols)
return
# for a cyclical task, things need to be sorted out already,
# so this object should have already been added to the appropriate sub-task
# can put an assertion here to make sure....
if task.circular:
return
task.append(obj, listonly, isdelete=isdelete, **kwargs)
def set(self, event, obj, newvalue, oldvalue):
# process "save_update" cascade rules for when an instance is attached to another instance
sess = object_session(obj)
if sess is not None:
if newvalue is not None and self.cascade is not None and self.cascade.save_update and newvalue not in sess:
mapper = object_mapper(obj)
prop = mapper.props[self.key]
ename = prop.mapper.entity_name
sess.save_or_update(newvalue, entity_name=ename)
def append(self, event, obj, item):
# process "save_update" cascade rules for when an instance is appended to the list of another instance
sess = object_session(obj)
if sess is not None:
if self.cascade is not None and self.cascade.save_update and item not in sess:
mapper = object_mapper(obj)
prop = mapper.props[self.key]
ename = prop.mapper.entity_name
sess.save_or_update(item, entity_name=ename)
def register_clean(self, obj):
if obj in self.new:
self.new.remove(obj)
if not hasattr(obj, '_instance_key'):
mapper = object_mapper(obj)
obj._instance_key = mapper.instance_key(obj)
if hasattr(obj, '_sa_insert_order'):
delattr(obj, '_sa_insert_order')
self.identity_map[obj._instance_key] = obj
attribute_manager.commit(obj)
def lazyload():
if self._should_log_debug:
self.logger.debug("deferred load %s group %s" %
(mapperutil.attribute_str(
instance, self.key), str(self.group)))
try:
pk = self.parent.pks_by_table[self.columns[0].table]
except KeyError:
pk = self.columns[0].table.primary_key
clause = sql.and_()
for primary_key in pk:
attr = self.parent.get_attr_by_column(instance, primary_key)
if not attr:
return None
clause.clauses.append(primary_key == attr)
session = sessionlib.object_session(instance)
if session is None:
raise exceptions.InvalidRequestError(
"Parent instance %s is not bound to a Session; deferred load operation of attribute '%s' cannot proceed"
% (instance.__class__, self.key))
localparent = mapper.object_mapper(instance)
if self.group is not None:
groupcols = [
p for p in localparent.props.values()
if isinstance(p.strategy, DeferredColumnLoader)
and p.group == self.group
]
result = session.execute(
localparent,
sql.select([g.columns[0] for g in groupcols],
clause,
use_labels=True), None)
try:
row = result.fetchone()
for prop in groupcols:
if prop is self:
continue
# set a scalar object instance directly on the object,
# bypassing SmartProperty event handlers.
sessionlib.attribute_manager.init_instance_attribute(
instance, prop.key, uselist=False)
instance.__dict__[prop.key] = row[prop.columns[0]]
return row[self.columns[0]]
finally:
result.close()
else:
return session.scalar(
localparent,
sql.select([self.columns[0]], clause, use_labels=True),
None)
def is_deleted(self, obj):
mapper = object_mapper(obj)
task = self.get_task_by_mapper(mapper)
return task.is_deleted(obj)
def unregister_object(self, obj):
#print "UNREGISTER", obj
mapper = object_mapper(obj)
task = self.get_task_by_mapper(mapper)
if obj in task.objects:
task.delete(obj)
def lazyload():
self.logger.debug("lazy load attribute %s on instance %s" %
(self.key, mapperutil.instance_str(instance)))
params = {}
allparams = True
# if the instance wasnt loaded from the database, then it cannot lazy load
# child items. one reason for this is that a bi-directional relationship
# will not update properly, since bi-directional uses lazy loading functions
# in both directions, and this instance will not be present in the lazily-loaded
# results of the other objects since its not in the database
if not mapper.has_identity(instance):
return None
#print "setting up loader, lazywhere", str(self.lazywhere), "binds", self.lazybinds
for col, bind in self.lazybinds.iteritems():
params[bind.key] = self.parent.get_attr_by_column(
instance, col)
if params[bind.key] is None:
allparams = False
break
if not allparams:
return None
session = sessionlib.object_session(instance)
if session is None:
try:
session = mapper.object_mapper(instance).get_session()
except exceptions.InvalidRequestError:
raise exceptions.InvalidRequestError(
"Parent instance %s is not bound to a Session, and no contextual session is established; lazy load operation of attribute '%s' cannot proceed"
% (instance.__class__, self.key))
# if we have a simple straight-primary key load, use mapper.get()
# to possibly save a DB round trip
if self.use_get:
ident = []
for primary_key in self.mapper.pks_by_table[
self.mapper.mapped_table]:
bind = self.lazyreverse[primary_key]
ident.append(params[bind.key])
return session.query(self.mapper).get(ident)
elif self.order_by is not False:
order_by = self.order_by
elif self.secondary is not None and self.secondary.default_order_by(
) is not None:
order_by = self.secondary.default_order_by()
else:
order_by = False
result = session.query(self.mapper,
with_options=options).select_whereclause(
self.lazywhere,
order_by=order_by,
params=params)
if self.uselist:
return result
else:
if len(result):
return result[0]
else:
return None
