python alchemy
1from sqlalchemy import Column, Integer, String, ForeignKey, Table
2from sqlalchemy.orm import relationship, backref
3from sqlalchemy.ext.declarative import declarative_base
4
5Base = declarative_base()
6
7author_publisher = Table(
8 "author_publisher",
9 Base.metadata,
10 Column("author_id", Integer, ForeignKey("author.author_id")),
11 Column("publisher_id", Integer, ForeignKey("publisher.publisher_id")),
12)
13
14book_publisher = Table(
15 "book_publisher",
16 Base.metadata,
17 Column("book_id", Integer, ForeignKey("book.book_id")),
18 Column("publisher_id", Integer, ForeignKey("publisher.publisher_id")),
19)
20
21class Author(Base):
22 __tablename__ = "author"
23 author_id = Column(Integer, primary_key=True)
24 first_name = Column(String)
25 last_name = Column(String)
26 books = relationship("Book", backref=backref("author"))
27 publishers = relationship(
28 "Publisher", secondary=author_publisher, back_populates="authors"
29 )
30
31class Book(Base):
32 __tablename__ = "book"
33 book_id = Column(Integer, primary_key=True)
34 author_id = Column(Integer, ForeignKey("author.author_id"))
35 title = Column(String)
36 publishers = relationship(
37 "Publisher", secondary=book_publisher, back_populates="books"
38 )
39
40class Publisher(Base):
41 __tablename__ = "publisher"
42 publisher_id = Column(Integer, primary_key=True)
43 name = Column(String)
44 authors = relationship(
45 "Author", secondary=author_publisher, back_populates="publishers"
46 )
47 books = relationship(
48 "Book", secondary=book_publisher, back_populates="publishers"
49 )