Class Parent

examples/versioned_rows/versioned_update_old_row.py:118–142

class Parent(VersionedStartEnd, Base):
    __tablename__ = "parent"
    id = Column(Integer, primary_key=True)
    start = Column(DateTime, primary_key=True)
    end = Column(DateTime, primary_key=True)
    data = Column(String)

    child_n = Column(Integer)

    child = relationship(
        "Child",
        primaryjoin=("Child.id == foreign(Parent.child_n)"),
        # note the primaryjoin can also be:
        #
        #  "and_(Child.id == foreign(Parent.child_n), "
        #  "func.now().between(Child.start, Child.end))"
        #
        # however the before_compile() above will take care of this for us in
        # all cases except for joinedload.  You *can* use the above primaryjoin
        # as well, it just means the criteria will be present twice for most
        # parent->child load operations
        #
        uselist=False,
        backref=backref("parent", uselist=False),
    )


class Child(VersionedStartEnd, Base):