Sqlalchemy, relation vs relationship

Question

In some sqlalchemy tutorials, relation function used to define sql-relationships. like this:

class Movie(DeclarativeBase):
    __tablename__ = "movies"

    movie_id = Column(Integer, primary_key=True)
    title = Column(String(100), nullable=False)
    description = Column(Text, nullable=True)
    genre_id = Column(Integer, ForeignKey('genres.genre_id'))
    genre = relation('Genre', backref='movies')
    release_date = Column(Date, nullable=True)

class Director(DeclarativeBase):
    __tablename__ = "directors"

    director_id = Column(Integer, primary_key=True)
    title = Column(String(100), nullable=False)
    movies = relation(Movie, secondary=movie_directors_table, backref="directors")

But some articles offering the relationship function, i.e:

class Address(Base):
     __tablename__ = 'addresses'
     id = Column(Integer, primary_key=True)
     email_address = Column(String, nullable=False)
     user_id = Column(Integer, ForeignKey('users.id'))
     user = relationship("User", backref=backref('addresses', order_by=id))

My question is: what is the differences between those two functions, and at least a reason to use each one.

Thanks is advance

Answer 1

According to docs, they are synonyms:

sqlalchemy.orm.relation(*arg, **kw)

A synonym for relationship().

And, actually:

Changed in version 0.6: relationship() was renamed from its previous name relation().

So, better use relationship() as it is the most "fresh" name of the two.