diff options
Diffstat (limited to 'lib/sqlalchemy/orm/mapper.py')
| -rw-r--r-- | lib/sqlalchemy/orm/mapper.py | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/lib/sqlalchemy/orm/mapper.py b/lib/sqlalchemy/orm/mapper.py index b4aee545e..c8df51b06 100644 --- a/lib/sqlalchemy/orm/mapper.py +++ b/lib/sqlalchemy/orm/mapper.py @@ -2297,6 +2297,41 @@ class Mapper( return None @HasMemoized.memoized_attribute + def _should_select_with_poly_adapter(self): + """determine if _MapperEntity or _ORMColumnEntity will need to use + polymorphic adaption when setting up a SELECT as well as fetching + rows for mapped classes and subclasses against this Mapper. + + moved here from context.py for #8456 to generalize the ruleset + for this condition. + + """ + + # this has been simplified as of #8456. + # rule is: if we have a with_polymorphic or a concrete-style + # polymorphic selectable, *or* if the base mapper has either of those, + # we turn on the adaption thing. if not, we do *no* adaption. + # + # this splits the behavior among the "regular" joined inheritance + # and single inheritance mappers, vs. the "weird / difficult" + # concrete and joined inh mappings that use a with_polymorphic of + # some kind or polymorphic_union. + # + # note we have some tests in test_polymorphic_rel that query against + # a subclass, then refer to the superclass that has a with_polymorphic + # on it (such as test_join_from_polymorphic_explicit_aliased_three). + # these tests actually adapt the polymorphic selectable (like, the + # UNION or the SELECT subquery with JOIN in it) to be just the simple + # subclass table. Hence even if we are a "plain" inheriting mapper + # but our base has a wpoly on it, we turn on adaption. + return ( + self.with_polymorphic + or self._requires_row_aliasing + or self.base_mapper.with_polymorphic + or self.base_mapper._requires_row_aliasing + ) + + @HasMemoized.memoized_attribute def _with_polymorphic_mappers(self) -> Sequence[Mapper[Any]]: self._check_configure() |