sqlalchemy - How to create one-to-one relationships with declarative

Question

I have two tables, foo and bar, and I want foo.bar_id to link to bar. The catch is that this is a one-way one-to-one relationship. bar must not know anything about foo. For every foo, there will be one and only one bar.

Ideally, after selecting a foo, I could do something like this:

myfoo.bar.whatever = 5 

How to accomplish this?

Answer 1

The documentation explains this nicely:

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    child = relationship("Child", uselist=False, backref="parent")

class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('parent.id'))

OR

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    child_id = Column(Integer, ForeignKey('child.id'))
    child = relationship("Child", backref=backref("parent", uselist=False))

class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)