def _load_for_state(self, state, passive):
if not state.key and \
(not self.parent_property.load_on_pending or not state.session_id):
return attributes.ATTR_EMPTY
instance_mapper = state.manager.mapper
prop = self.parent_property
key = self.key
prop_mapper = self.mapper
pending = not state.key
if (
(passive is attributes.PASSIVE_NO_FETCH or \
passive is attributes.PASSIVE_NO_FETCH_RELATED) and
not self.use_get
) or (
passive is attributes.PASSIVE_ONLY_PERSISTENT and
pending
):
return attributes.PASSIVE_NO_RESULT
session = sessionlib._state_session(state)
if not session:
raise orm_exc.DetachedInstanceError(
"Parent instance %s is not bound to a Session; "
"lazy load operation of attribute '%s' cannot proceed" %
(mapperutil.state_str(state), key))
# if we have a simple primary key load, check the
# identity map without generating a Query at all
if self.use_get:
if session._flushing:
get_attr = instance_mapper._get_committed_state_attr_by_column
else:
get_attr = instance_mapper._get_state_attr_by_column
dict_ = state.dict
if passive is attributes.PASSIVE_NO_FETCH_RELATED:
attr_passive = attributes.PASSIVE_OFF
else:
attr_passive = passive
ident = [
get_attr(state,
state.dict,
self._equated_columns[pk],
passive=attr_passive)
for pk in prop_mapper.primary_key
]
if attributes.PASSIVE_NO_RESULT in ident:
return attributes.PASSIVE_NO_RESULT
if _none_set.issuperset(ident):
return None
ident_key = prop_mapper.identity_key_from_primary_key(ident)
instance = Query._get_from_identity(session, ident_key, passive)
if instance is not None:
return instance
elif passive is attributes.PASSIVE_NO_FETCH or \
passive is attributes.PASSIVE_NO_FETCH_RELATED:
return attributes.PASSIVE_NO_RESULT
q = session.query(prop_mapper)._adapt_all_clauses()
# don't autoflush on pending
if pending:
q = q.autoflush(False)
if state.load_path:
q = q._with_current_path(state.load_path + (key, ))
if state.load_options:
q = q._conditional_options(*state.load_options)
if self.use_get:
return q._load_on_ident(ident_key)
if prop.order_by:
q = q.order_by(*util.to_list(prop.order_by))
for rev in prop._reverse_property:
# reverse props that are MANYTOONE are loading *this*
# object from get(), so don't need to eager out to those.
if rev.direction is interfaces.MANYTOONE and \
rev._use_get and \
not isinstance(rev.strategy, LazyLoader):
q = q.options(EagerLazyOption((rev.key, ), lazy='select'))
lazy_clause = self.lazy_clause(state)
if pending:
bind_values = sql_util.bind_values(lazy_clause)
if None in bind_values:
return None
q = q.filter(lazy_clause)
result = q.all()
if self.uselist:
return result
else:
l = len(result)
if l:
if l > 1:
util.warn(
"Multiple rows returned with "
"uselist=False for lazily-loaded attribute '%s' " %
prop)
return result[0]
else:
return None