diff options
Diffstat (limited to 'lib/sqlalchemy/orm/strategies.py')
| -rw-r--r-- | lib/sqlalchemy/orm/strategies.py | 90 |
1 files changed, 47 insertions, 43 deletions
diff --git a/lib/sqlalchemy/orm/strategies.py b/lib/sqlalchemy/orm/strategies.py index 1d0058ca2..0b22b8486 100644 --- a/lib/sqlalchemy/orm/strategies.py +++ b/lib/sqlalchemy/orm/strategies.py @@ -915,28 +915,21 @@ class SubqueryLoader(AbstractRelationshipLoader): # determine the immediate parent class we are joining from, # which needs to be aliased. - if len(to_join) > 1: - info = inspect(to_join[-1][0]) if len(to_join) < 2: # in the case of a one level eager load, this is the # leftmost "left_alias". parent_alias = left_alias - elif info.mapper.isa(self.parent): - # In the case of multiple levels, retrieve - # it from subq_path[-2]. This is the same as self.parent - # in the vast majority of cases, and [ticket:2014] - # illustrates a case where sub_path[-2] is a subclass - # of self.parent - parent_alias = orm_util.AliasedClass( - to_join[-1][0], - use_mapper_path=True) else: - # if of_type() were used leading to this relationship, - # self.parent is more specific than subq_path[-2] - parent_alias = orm_util.AliasedClass( - self.parent, - use_mapper_path=True) + info = inspect(to_join[-1][0]) + if info.is_aliased_class: + parent_alias = info.entity + else: + # alias a plain mapper as we may be + # joining multiple times + parent_alias = orm_util.AliasedClass( + info.entity, + use_mapper_path=True) local_cols = self.parent_property.local_columns @@ -949,35 +942,46 @@ class SubqueryLoader(AbstractRelationshipLoader): def _apply_joins( self, q, to_join, left_alias, parent_alias, effective_entity): - for i, (mapper, key) in enumerate(to_join): - - # we need to use query.join() as opposed to - # orm.join() here because of the - # rich behavior it brings when dealing with - # "with_polymorphic" mappers. "aliased" - # and "from_joinpoint" take care of most of - # the chaining and aliasing for us. - - first = i == 0 - middle = i < len(to_join) - 1 - second_to_last = i == len(to_join) - 2 - last = i == len(to_join) - 1 - - if first: - attr = getattr(left_alias, key) - if last and effective_entity is not self.mapper: - attr = attr.of_type(effective_entity) - else: - if last: - attr = getattr(parent_alias, key).\ - of_type(effective_entity) + + ltj = len(to_join) + if ltj == 1: + to_join = [ + getattr(left_alias, to_join[0][1]).of_type(effective_entity) + ] + elif ltj == 2: + to_join = [ + getattr(left_alias, to_join[0][1]).of_type(parent_alias), + getattr(parent_alias, to_join[-1][1]).of_type(effective_entity) + ] + elif ltj > 2: + middle = [ + ( + orm_util.AliasedClass(item[0]) + if not inspect(item[0]).is_aliased_class + else item[0].entity, + item[1] + ) for item in to_join[1:-1] + ] + inner = [] + + while middle: + item = middle.pop(0) + attr = getattr(item[0], item[1]) + if middle: + attr = attr.of_type(middle[0][0]) else: - attr = getattr(mapper.entity, key) + attr = attr.of_type(parent_alias) - if second_to_last: - q = q.join(parent_alias, attr, from_joinpoint=True) - else: - q = q.join(attr, aliased=middle, from_joinpoint=True) + inner.append(attr) + + to_join = [ + getattr(left_alias, to_join[0][1]).of_type(inner[0].parent) + ] + inner + [ + getattr(parent_alias, to_join[-1][1]).of_type(effective_entity) + ] + + for attr in to_join: + q = q.join(attr, from_joinpoint=True) return q def _setup_options(self, q, subq_path, orig_query, effective_entity): |