SQLAlchemy 泛型关系简单示例

使用SQLAlchemy创建泛型关系的简单示例

python
from sqlalchemy import create_engine, Column, Integer, String, ForeignKey
from sqlalchemy.orm import relationship, declarative_base
Base = declarative_base()
class Author(Base):
    __tablename__ = 'authors'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    books = relationship("Book", secondary="author_book_association")
class Book(Base):
    __tablename__ = 'books'
    id = Column(Integer, primary_key=True)
    title = Column(String)
class AuthorBookAssociation(Base):
    __tablename__ = 'author_book_association'
    author_id = Column(Integer, ForeignKey('authors.id'), primary_key=True)
    book_id = Column(Integer, ForeignKey('books.id'), primary_key=True)
engine = create_engine('sqlite:///:memory:')
Base.metadata.create_all(engine)

python
from sqlalchemy.orm import registry
mapper_registry = registry()
AuthorBookRelationship = relationship(
    "Book",
    secondary="author_book_association",
    back_populates="authors",
)
mapper_registry.map_imperatively(
    Author,
    column_prefix="author_",
    properties={
        "books": AuthorBookRelationship,
    },
)
mapper_registry.map_imperatively(
    Book,
    column_prefix="book_",
    properties={
        "authors": AuthorBookRelationship,
    },
)