Method _iterate_polymorphic_properties

lib/sqlalchemy/orm/mapper.py:2956–2982

Return an iterator of MapperProperty objects which will render into a SELECT.

(self, mappers=None)

            return None

    def _iterate_polymorphic_properties(self, mappers=None):
        """Return an iterator of MapperProperty objects which will render into
        a SELECT."""
        if mappers is None:
            mappers = self._with_polymorphic_mappers

        if not mappers:
            for c in self.iterate_properties:
                yield c
        else:
            # in the polymorphic case, filter out discriminator columns
            # from other mappers, as these are sometimes dependent on that
            # mapper's polymorphic selectable (which we don't want rendered)
            for c in util.unique_list(
                chain(
                    *[
                        list(mapper.iterate_properties)
                        for mapper in [self] + mappers
                    ]
                )
            ):
                if getattr(c, "_is_polymorphic_discriminator", False) and (
                    self.polymorphic_on is None
                    or c.columns[0] is not self.polymorphic_on
                ):
                    continue
                yield c

    @HasMemoized.memoized_attribute
    def attrs(self) -> util.ReadOnlyProperties[MapperProperty[Any]]: