python - 在不创建对象的情况下，sqlalchemy 中关系的另一端是什么类型？

Question

如何获得应该在关系另一端的类的名称？它是在创建关系时声明的。我想该信息应该在 sqlalchemy.orm.util.class_mapper 中

假设我们有这三个类以及它们之间的关系。
书 * --- 1 架子和
书 * --- * 作者

class Shelf(Base):
    __tablename__ = 'shelves'
    id = Column(Integer, primary_key = True)
    name = Column(String)
    #one-to-many books by backref in Book.shelf

    def __init__(self, name=""):
        self.name = name

class Book(Base):
    __tablename__ = 'books'
    id = Column(Integer, primary_key = True)
    title = Column(String)
    #many-to-one shelf
    shelf_id = Column(Integer, ForeignKey('shelves.id'))
    shelf = relationship(Shelf, backref=backref('books', order_by=id))
    def __init__(self, title=""):
        self.title = title

author_book = Table('author_book', metadata, 
                    Column('author_id', Integer, ForeignKey('authors.id')),
                    Column('book_id', Integer, ForeignKey('books.id'))
                    )

class Author(Base):
    __tablename__ = 'authors'
    id = Column(Integer, primary_key = True)
    name = Column(String)
    #many-to-many books
    books = relationship('Book', secondary=author_book, backref='authors')

    def __init__(self, name=""):
        self.name = name

从 class_mapper(Class).iterate_properties 我们可以很容易地得到不同的属性:ColumnProperty 和 RelationshipProperty。
应该有一种方法可以获取相关类的名称。有任何想法吗？

Answer 1

也许更简洁的解决方案。

for prop in class_mapper(Shelf).iterate_properties:
    if isinstance(prop, sqlalchemy.orm.RelationshipProperty):
       print prop.mapper.class_

双向使用一对多和多对多